Statistically Speaking

In this episode Miles is joined by Professor Luciano Floridi of Oxford University; Simon Whitworth of the UK Statistics Authority; and Pete Stokes from the ONS to talk about data ethics and public trust in official statistics. TRANSCRIPT MILES FLETCHER Hello, I'm Miles Fletcher, and in this episode of Statistically Speaking we're exploring data ethics and public trust in official statistics. In 2007, 15 years ago to the very day we are recording this, the UK Parliament gave the Office for National Statistics the objective of promoting and safeguarding the production and publication of official statistics that serve the public good. But what does, or should, the "public good" mean? How does the ONS seek to deliver it in practice? Why should the public trust us to act in their interests at a time of exponential growth in data of all kinds? Where are the lines to be drawn between individual privacy and anonymity on the one hand, the potential of data science to improve public services and government policies to achieve better health outcomes, even saving lives, on the other. Joining me to discuss these topics today are Simon Whitworth, Head of Data Ethics at the UK statistics authority, Pete Stokes, Director of the Integrated Data programme here at the ONS and Luciano Floridi, professor of philosophy and the ethics of information and director of the digital ethics lab at the Oxford Internet Institute. Professor let's start this big concept with you. What do you think Parliament meant when it said that the ONS should serve the public good in this context? LUCIANO FLORIDI It might have meant many things, and I suspect that a couple of them must have been in their minds. First of all, we know that data or information, depending on the vocabulary, has an enormous value if you know how to use it. And, collecting it and using it properly for the future of the country, to implement the right policies, to avoid potential mistakes and to see things in advance - knowledge is power, information is power. So, this might have been one of the things that they probably meant by "public good". The other meaning, it might be a little bit more specific...It's when we use the data appropriately, ethically, to make sure that some sector or some part of the population is not left behind, to learn who needs more help, to know what help and when to deliver it, and to whom. So, it's not just a matter of the whole nation doing better, or at least avoiding problems, but also specific sectors of the population being helped, and to make sure that the burden and the advantages are equally distributed among everybody. That's normally what we mean by public good and certainly, that analysis is there to serve it. MF So there's that dilemma between using the power of data to actually achieve positive outcomes. And for government, on the other hand, being seen as overbearing, or Orwellian, and spying on people through the use of data. LF That would be the risk that sometimes comes under the term "paternalism", that knowing a lot about your citizens might lead to the temptation of manipulating their lives, their choices, their preferences. I wouldn't over-emphasise this though. The kind of legislation that we have and the constraints, the rules, the double checking, make sure that the advantage is always in view and can more easily be squeezed out of the data that we accumulate, and sometimes the potential abuses and mistakes, the inevitable temptation to do the wrong thing, are kept in check. So yes, the State might use the government's political power, might misuse data, and so we need to be careful, but I wouldn't list that as my primary worry. My primary worry perhaps, would be under-using the data that we have, or making mistakes inadvertently. MF Do you think then, perhaps as a country, the UK has been too cautious in this area in the past? LF I don't think it has been too cautious, either intellectually or strategically. There's been a lot of talking about doing the right thing. I think it's been slightly cautious, or insufficiently radical, in implementing policies that have been around for some time. But we now have seen several governments stating the importance of that analysis, statistical approaches to evidence, and so on. But I think that there is more ambition in words than in deeds, so I would like to see more implementations, more action and less statements. Then the ambition will be matched by the actions on the ground. MF One of the reasons perhaps there might have been caution in the past is of course concern about how the public would react to that use of data. What do we know of public attitudes now in 2022, to how government bodies utilise data? LF I think the impression is that, depending on whom you ask, whether it is the younger population or slightly older people my age, people who lived in the 50s versus my students, they have different attitudes. We're getting used to the fact that our data are going to be used. The question is no longer are they going to be used, but more like, how and who is using them? For what purposes? Am I in charge? Can I do something if something goes wrong? And I would add also, in terms of attitude, one particular feature which I don't see sufficiently stressed, is who is going to help me if something goes wrong? Because the whole discussion, or discourse, should look more at how we make people empowered, so that they can check, they have control, they can go do this, do that. Well, who has the time, the ability, the skills, and indeed the will, to do that? It's much easier to say, look, there will be someone, for example the government, who will protect your rights, who you can approach, and they will do the right thing for you. Now we're getting more used to that. And so, I believe that the attitude is slightly changing towards a more positive outlook, as long as everything is in place, we are seeing an increasingly positive attitude towards public use of public data. MF Pete, your role is to make this happen. In practice, to make sure that government bodies, including the ONS, are making ethical use of data and serving the public good. Just before we get into that though, explain if you would, what sort of data is being gathered now, and for what purposes? PETE STOKES So we've got a good track record of supporting research use of survey data, that we collect largely in ONS, but on other government departments as well. But over the last few years, there's been an acceleration and a real will to make use of data that have been collected for other purposes. We make a lot of use now of administrative data, these are data that are collected by government not for an analytical purpose but for an operational purpose. For example, data that are collected by HMRC from people when they're collecting tax, or from the Department of Work and Pensions when they're collecting benefits, or from local authorities when they're collecting council tax - all of those administrative data are collected and stored. There's an increasing case to make those data available for analysis which we're looking to support. And then the other new area is what's often called "faster data", and these data that are typically readily available, usually in the public domain where you get a not so deep insight as you'd get from a survey of administrative data, but you could get a really quick answer. And a good example of that from within the ONS is that we calculate inflation. As a matter of routine, we collect prices from lots of organisations, but you can more quickly do some of that if you can pull some data that are readily available on the internet to give you those quicker indicators, faster information of where prices are rising quickly where they're dropping quickly. There's a place for all of these depending on the type of analysis that you want to do. MF This is another area where this ethical dilemma might arise though isn't it, because when you sit down with someone and they've agreed to take part in the survey, they know what they're going in for. But when it comes to other forms of information, perhaps tax information that you've mentioned already, some people might think, why do they want to know that? PS When people give their data to HMRC or to DWP as part of the process of receiving a service, like paying tax for example, I think people generally understand what they need to give that department for their specific purpose. When we then want to use this data for a different purpose, there is a larger onus on us to make sure that we are protecting those data, we're protecting the individual and that those data are only being used ethically and in areas of trust, specifically in the public interest. So, it's important that we absolutely protect the anonymity of the individuals, that we make sure where their data are used, and that we are not using the data of those data subjects as individuals, but instead as part of a large data-set to look for trends and patterns within those data. And finally, that the analysis that are then undertaken with them are explicitly and demonstrably in the public interest, that they serve the public good of all parts of society. MF And that's how you make the ethical side of this work in practice, by showing that it can be used to produce faster and more accurate statistics than we could possibly get from doing a sample survey? PS Yes, exactly, and sample surveys are very, very powerful when you want to know about a specific subject, but they're still relatively small. The largest sample survey that the ONS does is the Labour Force Survey, which collects data from around 90,000 people every quarter. Administrative datasets have got data from millions of people, which enables you to draw your insights not just at a national level and national patterns, but if you want to do some analysis on smaller geographic areas, administrative data gives you the power to do that when surveys simply don't. But, any and all use of data must go through a strict governance process to ensure that the confidentiality of the data subjects be preserved. And not only will the use be clearly and demonstrably in the public interest, but also, will be ethically sound and will stand up to scrutiny in that way as well. MF And who gets to see this stuff? PS The data are seen by the accredited researchers that apply to use it. So, a researcher applies to use the data, they're accredited, and they demonstrate their research competence and their trustworthiness. They can use those data in a secure lockdown environment, and they do their analysis. When they complete their analysis, those can then be published. Everybody in the country can see the results of those analyses. If you've taken part in a social survey, or you've contributed some data to one of the administrative sources that we make available, you can then see all the results of all the analysis that are done with those data. MF But when you say its data, this is where the whole process of anonymization is important, isn't it? Because if I'm an accredited researcher selling it to see names and addresses, or people's personal, sensitive personal information. PS No, absolutely not. And the researchers only get to see the data that they need for their analysis. And because we have this principle, that the data are being used as an aggregated dataset, you don't need to see people's names or people's addresses. You need to know where people live geographically, in a small or broad area, but not the specific address. You need to know someone's demographic characteristics, but you don't need to know their name, so you can't see their name in the data. And that principle of pseudonymisation, or the de-identification of data, before their used is really important. When the analyses are completed and the outputs are produced, those are then reviewed by an expert team at ONS, and so the data are managed by us to ensure that they are fully protected, wholly non-disclosive, and that it's impossible to identify a member of the public from the published outputs. MF Historically, government departments didn't have perhaps the best record in sharing data around other bodies for the public benefit in this way. But all that changed, didn't it? A few years back with a new piece of legislation which liberalised, to an extent, what the ONS is able to do. PS So, the Digital Economy Act, passed in 2017, effectively put on a standard footing the ability of other departments to make their data available for researchers in the same way that ONS had already been able to do since the 2007 System Registration Service Act. It gave us parity, which then gave other departments the ability to make their data available and allow us to help them to do so, to take the expertise that the ONS has in terms of managing these data securely, managing access to them appropriately, accrediting the researchers, checking all the outputs and so on, to give the benefit of our expertise to the rest of government. In order that the data that they hold, that has previously been underutilised arguably, could then be fully used for analyses to develop policies or deliver services, to improve understanding of the population or cohorts of the population or geographic areas of the country, or even sectors of industry or segments of businesses, for example, in a way that hasn't previously been possible, and clearly benefits the country overall. MF So the aim here is to make full use of a previously untapped reservoir, a vast reservoir, an ocean you might even say, of public data. But who decides what data gets brought in in this way? PS We work closely with the departments that control the data, but ultimately, those departments decide what use can be made of their data. So, it is for HMRC, DWP, the Department for Education, it's for them to decide which data they choose to make available through the Secure Research Service (SRS) or the Integrated Data Service (IDS) that we run in ONS. When they're supportive and recognise the analytical value of their data, we then manage the service where researchers apply to use those data. Those applications are then assessed by ONS first and foremost, we then discuss those requests and the use cases with the data owning departments and say, do you agree this would be a sensible use of your data? MF Is there an independent accreditation panel that reports to the UK statistics Authority Board, that assesses the request to use the data is in the public interest, that it serves the public good? PS The ethics of the proposal are also assessed by an independent ethics advisory committee, whether it's the national statistician's data ethics advisory committee or another. There's a lot of people involved in the process to make sure that any and every use of data is in the public interest. MF From what we know from the evidence available, certainly according to the latest public confidence and official statistics survey - that's a big biannual survey run by the UK Statistics Authority (UKSA) - I guess for that, and other reasons, public trust remains high. The Survey said 89% of people that gave a view trusted ONS, and 90% agreed that personal information provided to us would be kept confidential. But is there a chance that we could lose some of that trust now, given that there is much greater use, and much greater sharing, of admin data? It should be said that it doesn't give people the chance to opt out. PS I think one of the reasons that trust has remained high is because of the robust controls we have around the use of data. Because of the comprehensive set of controls and the framework that we put around use of data that protects confidentiality, that ensures that all uses are in the public interest. And another important component of it is that all use of data that we support is transparent by default. So, any analyst wanting to use data that are held by ONS, or from another department that we support, we publish the details of who those analysts are, which data they're using, what they're using them for, and then we require them to publish the outputs as well. And that transparency helps maintain public trust because if someone wants to know what their data is being used for, they can go to our website or directly to the analyst, and they can see the results tangibly for themselves. Now, they might not always agree that every use case is explicitly in the public interest, but they can see the thought process. They can see how the independent panel has reached that conclusion, and that helps us to retain the trust. There's a second half of your question around whether there is a risk of that changing. There is always a risk but we are very alive to that, which is why as we built the Integrated Data Service, and we look to make more and more government data available, that we don't take for granted the trust we've already got, and that we continue to work with the public, and with privacy groups, to make sure that as we build the new service and make more data available, we don't cross a line inadvertently, and we don't allow data to be used in a way that isn't publicly acceptable. We don't allow data to be combined in a way that would stretch that comfort. And this is that kind of proactive approach that we're trying to take, that we believe will help us retain public trust, despite making more and more data available. MF Professor Floridi, we gave you those survey results there, with people apparently having confidence in the system as it stands, but I guess it just takes a couple of negative episodes to change sentiment rapidly. What examples have we seen of that, and how have institutions responded? LF I think the typical examples are when data are lost, for example, inadvertently because of a breach and there is nobody at fault, but maybe someone introduced the wrong piece of software. It could be a USB, someone may be disgruntled, or someone else has found a way of entering the database - then the public gets very concerned immediately. The other case is when there is the impression, which I think is largely unjustified, but the impression remains, that the data in question are being used unjustly to favour maybe some businesses, or perhaps support some policies rather than others. And I agree with you, unfortunately, as in all cases, reputation is something very hard to build and can be easily lost. It's a bit unfair, but as always in life, building is very difficult but breaking down and destroying is very easy. I think that one important point here to consider is that there is a bit of a record as we move through the years. The work that we're talking about, as we heard, 2017 is only a few years ago, but as we build confidence and a good historical record, mistakes will happen, but they will be viewed as mistakes. In other words, there will be glitches and there will be forgiveness from the public built into the mechanism, because after say 10 or 15 years of good service, if something were to go wrong once or twice, I think the public will be able to understand that yes, things may go wrong, but they will go better next time and the problem will be repaired. So, I would like to see this fragility if you like, this brittle nature of trust, being counterbalanced by a reinforced sense of long-term good service that you know delivers, and delivers more and more and better and better, well then you can also build a little bit of tolerance for the occasional mistakes that are inevitable, as in everything human, they will occur once or twice. MF Okay, well, touching my mic for what would in effect be my desk, I can say that I don't think ONS has had an episode such as you describe, but of course, that all depends on the system holding up. And that seems a good point to bring in Simon Whitworth from the UK Statistics Authority, as kind of the overseeing body of all this. Simon, how does the authority go about its work? One comment you see quite commonly on social media when these topics are discussed, is while I might trust the body I give my data to, I don't trust them not to go off and sell it, and there have been episodes of data being sold off in that way. I think it's important to state isn't it, that the ONS certainly never sells data for private gain. But if you could talk about some of the other safeguards that the authority seeks to build into the system. SIMON WHITWORTH The big one is around the ethical use of data. The authority, and Pete referred to this, previously back in 2017, established something called the National Statisticians Data Ethics Advisory Committee, and that's an independent committee of experts in research, ethics and data law. And we take uses of data to that committee for their independent consideration. And what's more, we're transparent about the advice that that committee provides. So, what we have done, what we've made publicly available, is a number of ethical principles which guide our work. And that committee provide independent guidance on a particular use of data, be they linking administrative data, doing new surveys, using survey data, whatever they may be, they consider projects from across this statistical system against those ethical principles and provide independent advice and guidance to ensure that we keep within those ethical principles. So that's one thing we do, but there's also a big programme of work that comes from something that we've set up called the UK Statistics Authority Centre for Applied Data Ethics, and what that centre is trying to do is to really empower analysts and data users to do that work in ethically appropriate ways, to do their work in ways that are consistent with those ethical principles. And that centres around trying to promote a culture of ethics by design, throughout the lifecycle of different uses of data, be they the collection of data or the uses of administrative data. We've provided lots of guidance pieces recently, which are available on our website, around particular uses of data - geospatial data, uses of machine learning - we've provided guidance on public good, and we're providing training to support all of those guidance pieces. And the aim there is, as I say, to empower analysts from across the analytical system, to be able to think about ethics in their work and identify ethical risks and then mitigate those ethical risks. MF You mentioned the Ethics Committee, which is probably not a well-known body, independent experts though you say, these are not civil servants. These are academics and experts in the field. Typically, when do they caution researchers and statisticians, when do they send people back to think again, typically? SW It's not so much around what people do, it's about making sure how we do it is in line with those ethical principles. So, for example, they may want better articulations of the public good and consideration of potential harms. Public good for one section of society might equal public harm to another section of society. It's very often navigating that and asking for consideration of what can be done to mitigate those potential public harms and therefore increase the public good of a piece of research. The other thing I would say is being transparent. Peter alluded to this earlier, being transparent around data usage and taking on board wherever possible, the views of the public throughout the research process. Encouraging researchers as they're developing the research, speaking to the public about what they're doing, being clear and being transparent about that and taking on board feedback that they receive from the public whose data they're using. I would say that they're the two biggest areas where an estate provides comments and really useful and valuable feedback to the analytical community. MF Everyone can go online and see the work of the committee, to get the papers and minutes and so forth. And this is all happening openly and in a comfortable way? SW Yes, absolutely. We publish minutes of the meetings and outcomes from those meetings on the UK Statistics Authority's website. We also make a range of presentations over the course of the year around the work of the committee and the supporting infrastructure that supports the work because we have developed a self-assessment tool which allows analysts at the research design phase to consider those ethical principles, and different components of the ethical principles, against what they're trying to do. And that's proved to be extremely popular as a useful framework to enable analysts to think through some of these issues, and I suppose move ethics from theory to something a bit more applied. In terms of their work last year, over 300 projects from across the analytical community, both within government and academia, used that ethics self-assessment tool, and the guidance and training that sits behind it is again available on our website. MF I'm conscious of sounding just a little bit sceptical, and putting you through your paces to explain how the accountability and ethical oversight works, but can you think of some examples where there's been ethical scrutiny, and research outcomes having satisfied that process, have gone on to produce some really valuable benefits? SW ONS has done a number of surveys with victims of child sex abuse to inform various inquiries and various government policies. They have some very sensitive ethical issues that require real thinking about and careful handling. You know, the benefits of that research has been hugely important in showing the extent of child sex abuse that perhaps previously was unreported and providing statistics to both policymakers and charities around experiences of child sex abuse. In terms of administrative data, yes, there are numerous big data linkage projects that have come to ONS and have been considered by ONS, in particular, linkage surveys that follow people over time. Linkages done over time provide tremendous analytical value, but of course need some careful handling to ensure that access to that data is provided in an ethically appropriate way, and that we're being transparent. So those are the two I think of, big things we are thinking about in an ethically appropriate way. And being able to do them in an ethically appropriate way has really allowed us to unleash the analytical value of those particular methods, but in a way that takes the public with us and generates that public trust. MF Pete, you are part of the organisation that in fact runs an award scheme to recognise some of the outstanding examples of the secure use of data? PS We do, and it's another part of promoting the public benefit that comes from use of data. Every year we invite the analysts who use the Secure Research Service (SRS), or other similar services around the country, to put themselves forward for research excellence awards. So that we can genuinely showcase the best projects from across the country, but then also pick up these real examples of where people have made fantastic use of data, and innovative use of data, really demonstrating the public good. We've got the latest of those award ceremonies in October this year, and it's an open event so anybody who is interested in seeing the results of that, the use of data in that way, they would be very welcome to attend. MF Give us a couple of examples of recent winners, what they've delivered. PS One of the first award winners was looking at the efficacy of testing that was done for men who may or may not have been suffering from prostate cancer, and it analysed when if a person was given this test, what was the likelihood of its accuracy, and therefore whether they should start treatment, and the research was able to demonstrate that actually, given the efficacy, that it wasn't appropriate to treat everyone who got a positive test, because there was risk of doing more harm than good if it had persisted, which is really valuable. But this year, we'll be seeing really good uses of data in response to the pandemic, for example, tying this back to the ethics, when you talk about the use of data made during the pandemic in retrospect, it's clearly ethical, it's clearly in the public interest. But, at the start of the pandemic, we had to link together data from the NHS on who was suffering from COVID which was really good in terms of the basic details of who had COVID and how seriously and sadly, whether they died, but it missed a lot of other detail that helps us to understand why. We then linked those data with data from the 2011 Census where you can get data on people's ethnic group, on their occupation, on their living conditions, on the type and size of the family they live with, which enable much richer insights, but most importantly, enabled government to be able to target its policy at those groups who were reluctant to get the vaccination to understand whether people were suffering from COVID due to their ethnicity, or whether it was actually more likely to be linked to the type of occupation they did. Really, really valuable insights that came from being able to link these data together, which now sounds sensible, but at the time did have those serious ethical questions. Can we take these two big datasets that people didn't imagine we could link together and and keep the analyses ethically sound and in the public interest. What's what we were able to do. MF That's certainly a powerful example. But before we pat ourselves on the back too much for that survey I mentioned, some of the research we've been doing at the ONS does suggest that there is nevertheless a hardcore cohort of sceptics on all of this. Particularly, it is suggested, among the older age groups, the over 55's in particular. I mentioned the social media reaction you see as well. Kind of ironic you might think, given the amount of data that big social media platforms and other private organisations hold on people. Professor, do you think there's a paradox at work there? People are apparently inclined not to trust public bodies, accountable public bodies, but will trust the big social media and internet giants? Or is it just a question of knowledge, do you think? LF I think it might be partly knowledge, the better you know the system, who is doing what, and also the ability to differentiate between the different organisations and how they operate, under what kind of constraints, how reliable they are, etc, versus for example, commercial uses, advertisement driven, etc. The more you know, and it happens to be almost inevitably the younger you are, the more you might be able to see with a different kind of degree of trust, but also almost indifference, toward the fact that the data are being collected and what kind of data are being collected. I think the statistics that you were mentioning seem to be having an overlapping feature. A less young population, a less knowledgeable population, is also the population that is less used to social media, sharing, using data daily, etc. And is also almost inevitably a little bit more sceptical when it comes to giving the data for public good, or knowing that something is going to be done by, for example, cross referencing different databases. On the other side, you find the slightly younger, the more socially active, the kids who have been growing with social media - and they are not even on Facebook these days anymore, as my students remind me, Facebook is for people like me - so let's get things right now, when it comes to Tiktok, they know that they are being monitored, they know that the data is going to be used all over the place. There is a mix of inevitability, a sense of who cares, but also a sense of, that's okay. I mean data is the air you breathe, the energy you must have, it's like electricity. We don't get worried every time we turn on the electricity on in the house because we might die if someone has unreliably connected the wires, we just turn it on and trust that everything is going to be okay. So, I think that as we move on with our population becoming more and more well acquainted with technology, and who does work with the data and what rules are in place, as we heard before, from Simon and Pete, I mean, there are plenty of frameworks and robust ways of double checking that nothing goes wrong, and if something goes wrong, it gets rectified as quickly as possible. But the more we have that, I think the less the sceptics will have a real chance of being any more than people who subscribe to the flat earth theory. But we need to consider that the point you made is relevant. A bit of extra education on the digital divide, which we mentioned implicitly in our conversation today. Who is benefiting from what? And on which side of the digital innovation are these people placed? I think that needs to be addressed precisely now, to avoid scepticism which might be not grounded. MF I hope through this interesting discussion we've managed to go some way to explaining how it's all done, and why it's so very important. Simon Whitworth, Pete Stokes, Professor Luciano Floridi, thank you very much indeed for taking part in Statistically Speaking today. I'm Miles Fletcher and thanks for listening. You can subscribe to new episodes of this podcast on Spotify, Apple podcasts and all the other major podcast platforms. You can comment or ask us a question on Twitter at @ONSFocus. Our producer at the ONS is Julia Short. Until next time, goodbye

David Freeman and Nicola White join Miles to discuss how the Office for National Statistics (ONS) tracks employment and pay across the UK. Transcript: Hello and welcome again to Statistically Speaking, the Office for National Statistics podcast. In this episode, we enter the world of work and clock on for a shift with the ONS labour market team. We'll explore how they keep track of employment and pay across the UK and find out how the figures we hear so much about in the news should really be interpreted. At your service, are employees of the month, our head of labour market and household statistics David Freeman, and later on his colleague, senior statistician Nicola White. David, let's start with the basics. And one common misconception you still hear around the official statistics on unemployment is that they're based on the number of people claiming out of work benefits. And so, the theory goes therefore, that they're subject to manipulation in some way. But to be absolutely clear, the figures don't come from any other government department. This is data that comes from the ONS talking directly to real people, in their tens of thousands. DAVID FREEMAN That's absolutely right, Miles. The bulk of the information that we publish as part of our labour market statistics come from something called the 'Labour Force Survey'. As this is one of our big household surveys, every three months we sample 40,000 households across the UK. And we go and we interview the people in those households about their labour market status. So, are they working, are they not working. We also gather a lot of information about the people in those households, what age they are, whether they have got a disability, what ethnic group [they belong to], which gives a us rich picture of the UK labour market. MILES FLETCHER And by the standards of any survey, any regular survey, that's a huge sample isn't it. I know we don't go in for superlatives, but it's possibly the biggest household survey regularly undertaken of any kind? DAVID FREEMAN I think it is the biggest one in the UK, outside of the Census of course, and again, through the data that we use, we'll learn about the labour market, but the data will also feed into things like population estimates. So quite a wide range of uses, but its core purpose is really trying to measure the UK labour market. MILES FLETCHER And it's that time spent with people to gather a whole raft of data from them, and at scale, that can give a localised picture, which is so important too. DAVID FREEMAN Absolutely, we get a lot of information from the Labour Force Survey, either by age groups, by country of birth, also by regional level, and we have an annual version of the Labour Force Survey where we put the data together across a longer time period, which means we can get data down to things like local authority levels as well which is important for local government. MILES FLETCHER And how do we choose people to take part? DAVID FREEMAN It's a totally random process. So we have access to the postcode directory for the UK, which is effectively a list of all the households in the UK, and we take a random sample of those. However, we make sure within taking that sample that we're represented across the country. So within each local authority area, we've got enough people to be able to give us a robust estimate of what's happening there. MILES FLETCHER You stay in the survey a little while, don't you? DAVID FREEMAN You do, that's right, and that's one of the strengths of the Labour Force Survey. If you're selected to take part, you are in there for what we call "five waves". So if you're selected in January, we'll also come back and talk to you again in April, July, October and the following January. And that's important because not only do we find out what people are doing now, as you say we find out how people have changed, and whether they have moved into employment, out of employment, how have their circumstances changed. And that gives a deep insight into how people are flowing through the labour market and changing over time. MILES FLETCHER So, big sample, lots of data coming in. When it comes to the analysis though, essentially, we group people under three big categories. Now the first of those is employment. It sounds self-evident, but what is the definition of an employed person? DAVID FREEMAN To be employed is to be someone who has done paid work in the reference week, so when we interview people we'll say, what were you doing in the week before we're interviewing you? They are considered employed if they have done paid work for a minimum of one hour in that week. So the bar is, you could say it's quite low, in terms of one hour of work a week. But we have looked, and not that many people work that little in a week – less than 3% of people work less than five hours. So, as well as you'll get paid, we have a couple of other areas as well. We cover people who are employees, so employed by a company, the self-employed, people in government training schemes and people who work for their family business and might not get a wage packet but benefit from working for that business. MILES FLETCHER What is the average number of hours that employed people do? DAVID FREEMAN Overall, the average is around about 31 hours a week, and that does differ between if you're full time or part-time. So if you're full time, then the average is around 36. If you're part time, the average is around 16 hours a week. MILES FLETCHER Okay, so that's a working week. Now who is unemployed? Technically speaking. DAVID FREEMAN The technical definition of unemployed, there are three elements to it. Firstly, you've got to be not employed, so not doing any paid work. But you must also be actively seeking work in the previous four weeks. So that means applying for jobs, going to interviews, looking through listings, etc. And finally, you must be available to start work in the next two weeks. So you have got to be available to start a job within the next fortnight after we interview you. Again, another international definition used across the world to define who's unemployed. MILES FLETCHER And how long do you have to be unemployed to be classed as long-term unemployed? Because that's a very important category to understand as well. DAVID FREEMAN To be considered long-term unemployed, a person must have been in that position for a year or more. MILES FLETCHER What's the average time that people are currently spending unemployed? DAVID FREEMAN It's a bit hard to say, we don't have a technical age or an average time, but the majority of people who are unemployed have been unemployed for less than six months. So people moving into unemployment after having recently lost a job or moving through unemployment to get to a job. And it's just under 1 in 3, who have been unemployed for more than a year. MILES FLETCHER So if you don't satisfy any of those two definitions. You're not doing any kind of paid work and you're not actively seeking it in the way you've described, where does that leave you? DAVID FREEMAN Well, that leaves you in a third group that we call the "economically inactive". And so these people are not in work, and are either not actively seeking work, or are unavailable to start work. So you can be looking for work and not available, and you'd be economically inactive, or you might be available and not looking, and again, you'd be economically inactive there. And the sort of people included in this category are the sort of people who may be looking after family or home, they are stay-at-home parents, or they have caring responsibilities that mean they can't work. They might have a long-term illness or disability which means they are not able to work, or they may have retired. It's the people who aren't working and are not looking or available for work. MILES FLETCHER One contentious area under this definition of the economically inactive is a group that swells and contracts according to the economic cycle, and it's that group of people who are unable to work and are collecting benefits. What do we understand about that group at the moment? DAVID FREEMAN That group as you say, it does change over time. And the reason for that is because people on benefits depend on the rules around those benefits. So, over the years we have published something we call the "claimant count". This counts people claiming benefits and the main reason they're claiming benefits is because they're out of work. MILES FLETCHER And that used to be the main measure of our unemployment, as it was understood. DAVID FREEMAN You're absolutely right. If we go back to the early mid 90s, it was a lead measure. But at that point the rules around the benefits were such that the official unemployment count and the benefit count was about the same. However, when we moved to Jobseeker's Allowance in the late 90s, the rules changed on benefits. So fewer unemployed qualified for the benefits, and the two measures did diverge there. MILES FLETCHER It's been said that there's a very large group now who are on out of work benefits alone, and that is hidden unemployment? DAVID FREEMAN Some of these people will be unemployed if they're out of work, and actively seeking or available to work. However, out of work benefits will also include people who we would class as economically inactive. Such as people who have a long-term illness or disability that prevents them from working. They'll be getting out of work benefits because they're not working, but because they're not able to look for work, or not actively looking for work, we wouldn't count them in our unemployment statistics. So yes, there are a lot of people on out of work benefits, more than we would count as unemployed. But not all these people would fit that definition of unemployed that we use. MILES FLETCHER But nonetheless a very important indicator when you're thinking about how people might be helped into work. DAVID FREEMAN That's right. Yeah, and and it indicates what that potential workforce could be. But obviously, some of these people may need some help to get themselves into a position where they're able to look for work and gain employment. MILES FLATCHER Okay, well what that briefly explained, is how the headline measures - you might like to call them your classic ONS measure of employment and unemployment - work. But one criticism that you might care to make about this system is that it takes a while to process and the numbers when they come out...there's a bit of a lag isn't there. DAVID FREEMAN There is a little bit of a lag, again because of the size of the sample, the amount of data we have to process and the fact that we have to make sure we're getting enough responses in. There's about a six-week lag between the end of the period we're looking at and the data being published into the public domain. MILES FLATCHER So in order to speed things up a bit, and to have a timelier indicator of what was happening with employment, and this came in very useful with the arrival of the pandemic, we've been using faster sources of information to supplement the headline employment figures. Can you talk us through that? What progress has been made and how useful these other sources of data have been? DAVID FREEMAN Yeah, so probably the biggest one that we've been using throughout the pandemic has been the counting of people for the real time tax information from the Revenue and Customs department. So this is a big database that HMRC hold, and it contains information about everyone on a payroll. So if you are on a pay as you earn scheme, all your information is collated in HMRC for the purposes of calculating your tax. At the end of 2019, we started working with HMRC on publishing regular data from that system. I counted the number of people on payroll schemes and how much they're earning. The benefits of this are that it is a complete count of people on the pay as you earn scheme, so it gives us lots of information, meaning we can analyse smaller levels and small groups of people without impacting on the confidentiality of the data. When the pandemic started, we worked with HMRC to see if we could speed the data up, because previously it was at the same sort of pace as the Labour Force Survey, so about six weeks, and we managed to move to what we call a flash estimate. This means we can publish the data for a particular month within three weeks of the end of that month, which is so much faster and was a real benefit at the beginning of the pandemic. Getting information quickly about what was happening to employees on tax schemes. MILES FLETCHER And that was vital wasn't it, to inform the policy response to the pandemic when it arrived. Because you know, waiting a few weeks could have been too late for a lot of people. DAVID FREEMAN It could have been, and this is a big step forward in using this local administrative data in the labour market, and we've carried on doing that flash estimate. And as well as that we've been, over the pandemic period and up to the present day, adding more and more information from the pay as you earn tax data. So, a company produces data for a local authority level, we also do it by regional and industry. So, lots of information much more quickly than we can get it from our survey data. MILES FLETCHER You could say we've got the best of both worlds now. We've got the rich data coming out of the Labour Force Survey. But on the other hand, we've also got the much quicker data coming hot off the systems of HMRC to give that flash picture as you described it. DAVID FREEMAN One of the things that has been very developed over the pandemic is having this extra data and it provides a very, very rich picture. And when you put it together, you do get a very, very good picture of what's happening in the economy. I mean, the next step is to try and actually bring these data sources together. So linking data from the tax system to survey data, and trying to exploit even more, the benefits of having these sorts of information available. MILES FLETCHER Do you think we'll get to the point where we replace the survey completely? Or will it continue to have that very important central role? DAVID FREEMAN I think surveys will always have a central role. The tax data is brilliant. It does only cover employees, so we don't we don't cover the self-employed, you don't cover government trainees or people working for their family business. Also, the level of information we get from the Labour Force Survey is much bigger than we get from administrative data. On the tax system, we merely have information that's relevant to people paying tax. So that means we don't get a lot of the information that we get from labour force surveys - whether someone's got a disability, what their ethnic group is, what their nationality is - and these are all important variables in terms of informing government policy and giving a picture of what's happening in the UK. MILES FLETCHER You mentioned that the tax data was a development that was already in progress before the pandemic, but it was sped up given the urgency of that situation, but other sources of data have been coming in as well? DAVID FREEMAN Another big source of data that we've been working with over the pandemic period has been the online job vacancies data from a company called Azuna, who we've been partnering with over the period. And this has been another big step forward in calculating the number of vacancies in the UK economy. The data we are getting is really really timely, so we can take a download of data on the Friday, and we're publishing it the next week. So really timely. And, the information you're getting in an online job vacancy means we can look at things like where the vacancy is, so what geography it's located in, and some indication of the skills or the occupation of that vacancy as well. MILES FLETCHER Obviously, if you think about impacts of the pandemic for quite a period, over the last two years, when you add it all up, we spent a lot of time chained to our laptops, in many cases, working from home. How has that rubbed off on the workforce now, and what do we think is the lasting impact of the working from home trend? DAVID FREEMAN Certainly, on the latest data we've got, it does look like there's been a bit of a shift in terms of the number of people who work at home on a regular basis. Prior to the pandemic, fewer than three in 10 people had ever worked from home at any point, whereas if you look at the most recent data, around 35% of people are working from home regularly. So that 1 in 3 people are now doing some work at home during the working week. MILES FLETCHER So that's a huge change and we reckon that is, to some extent, showing signs of lasting? DAVID FREEMAN It does look like it is lasting. Home working doesn't necessarily work for everyone. When we did the analysis, there's quite a few professions or occupations where homework is relatively low. That's particularly in the caring occupations, retail, catering and construction, where it's hard, or if not impossible, to work from home. MILES FLETCHER We'll have to see how that develops over the months ahead. But another phenomenon that was spotted as we emerged from the pandemic was what's been called 'The Great Resignation'. Over 50s apparently disengaging with the labour market, and that I guess, is them going from employment in large numbers into the 'economically inactive' category? What do we know about that? DAVID FREEMAN You're absolutely right. This is something we've seen particularly in the last 12 months, people over 50 are moving out of the labour market into economic inactivity. Some of these people are retiring, so particularly the over 60s, most of those people are retiring. However, for the people aged 50 to 59, a lot of them are retiring for health reasons. They've developed a long-term illness, which again may be related to COVID, which is preventing them from carrying on with work. And this is having an impact on the overall labour market because the employment rate is still lagging behind where we were pre-pandemic, and a lot of that is down to these people moving outside into economic inactivity. MILES FLETCHER That's an important factor because other ONS statistics tell us that there were some 800,000 people who report, or we estimate, are suffering the effects of long COVID. So that would be a big factor in this, one might think, and it really isn't a question then of people having had a taste of being at home all the time and thinking, "Oh I just don't want to go back to work. Let's call it a day now". DAVID FREEMAN You're right. So the older people aged 60+, again, particularly people who have got a private pension and won't rely on the state pension, it is that retirement. But say for those 50-59s, while some of them are retiring early, there are people who believe themselves too ill to work MILES FLETCHER And what do we understand then from our lifestyle survey? About how people's patterns of leisure and work have changed? DAVID FREEMAN There are a few things to think about again, will the people who have moved out of the workforce want to go back into the workforce. Looking at those over 60, only about 18% of those want to go back and will consider returning to work. Whereas those in their 50s, just over half would consider returning to work, but looking for a job that suits their skills and would suit their lifestyle. So, people wanting more flexible work and something that will fit around their caring responsibilities as well. MILES FLETCHER So overall, how do we think the UK did in terms of dealing with a pandemic? And particularly its impact on the labour market compared with other countries? Did they see these kind of impacts as well? DAVID FREEMAN It's quite interesting when you look at the impact of the pandemic across different countries. In terms of the UK, we have a very similar pattern to the rest of Europe. We saw a drop off in employment rate at the start of the pandemic and then gradual increases. But that drop off in employment was about 2 to 3% of the employment rate, and that's in stark contrast to the USA and Canada where the pandemic impact was much greater in terms of falling employment - about nine to 10 percentage points of the employment rate. Moving onto inactivity, what seems to be the difference is the coronavirus job retention scheme in the UK, and similar schemes across Europe, kept people linked to their job and in employment, rather than moving into unemployment. Unemployment remains, again in the UK and across Europe, relatively low. But all countries, including the USA and in Europe as well, saw an increase in the level of inactivity during the pandemic. MILES FLETCHER So overall the UK not too exceptional really, in how governments responded to the impacts of a pandemic, and how those effects played out on the labour force. DAVID FREEMAN Not very different at all at the beginning of the pandemic. We're seeing a little bit of a difference now, and we touched on it earlier in terms of economic inactivity, is that the UK employment rate is still a bit below where it was pre pandemic, whereas the EU and USA and Canada, they've got back to about where they were at the beginning of 2020. This links to the over 50s moving out of the workforce. We're still a little bit behind other European countries at the moment. MILES FLETCHER And explains perhaps why the over 50s are the subject of particular research, extra research going on now to understand what's really going on there. DAVID FREEMAN Yeah, absolutely. Because that does seem to be the difference between us and the rest of Europe. MILES FLETCHER Okay, well I mentioned earlier on, the richness of the data that we get from the Labour Force Survey, and when you delve into the data, you get to explore some quite interesting topics. And one of them we uncovered the other day was that even in 2022, there are still some jobs that are dominated by one gender. Tell us about that. DAVID FREEMAN Yeah, so this is a really interesting thing. We do put out regular data, where we go right into the detail of some of the occupations. And it is interesting when you look at the sort of gender split in some of these jobs. So, there are a few jobs where we have hardly any women at all doing them, so that includes ship officers and metal workers, and at the other end of the spectrum, we've got very few men who say they are dancers or choreographers. MILES FLETCHER You might be less surprised to hear that pipelayers tend to be all male, but also veterinary nurses are almost exclusively female. DAVID FREEMAN That's right. And again, if you look at other occupations, that are predominantly female, they are things like midwives, school secretaries, PA's and secretaries, child minders, nursery nurses and medical secretaries. And then if you go to the occupations that are predominantly male, they're very much in the construction space, so carpenters, bricklayers, electricians and plumbers. MILES FLETCHER How do we classify people into jobs? We don't just listen to how people describe themselves. You have to fit into some classification, don't you? How does that work? DAVID FREEMAN Well, we have got a classification, it's called a 'standard occupational classification', and that gets updated regularly. The latest version was updated in 2020. And the way we classify people, when we do the interviews as part of the Labour Force Survey, we ask them what their occupation is. And then we take that description, and we match it onto our list of occupations. There are hundreds of potential occupations. We've got a computer programme that helps when you put the description in, it'll narrow it down to a few options, and then the interviewer can pick the most suitable of those options to match what the person has told us. MILES FLETCHER And that makes the figures internationally comparable. Again, you can't tell the Labour Force Survey, well, I'm an image consultant. They'd have to find a way of matching that against one of the definitions, and I see we were asked the other day whether 'Social Media Influencer' was a classified job, it turns out it isn't. They're either marketing associates, or actors and presenters, it turns out. These classifications, they're reviewed every 10 years or so aren't they, perhaps the next update will recognise a job like that. DAVID FREEMAN If it grows in terms of importance and the number of people doing it, it's quite likely it could end up with a classification. I mean, the latest update started including programmers as a separate job description. They were lumped in with other things in earlier classifications, again because of a growing occupation. MILES FLETCHER It's quite a good test this. If your mum asks you if you've got a proper job yet. If you can point to the standard occupational classification, I think that that'll answer the question for her quite satisfactory wouldn't it. By the way, recent additions are coffee shop workers, not surprisingly, given the huge growth in coffee serving establishments, what other ones have been officially designated recently? DAVID FREEMAN Lots of jobs linked around the internet and web development and website development as well. You go back 15 or 20 years and it didn't even exist. And things like 'Play Workers' as well, with the use of child minding and child play facilities, they're also new additions to the list. MILES FLETCHER So, working in the gig economy, you know, the hours might be irregular, you might be on a zero hours contract, but nevertheless, chances are you're your job is officially recognised. DAVID FREEMAN Almost certainly, even if your job may not have an official designation, you would still be fitting into the framework somewhere. MILES FLETCHER And it might be worth noting since we're sitting in the ONS, that data analysts have only been recently recognised as an official classified occupation. Well, just as important as finding out what people do is the whole question of how much they get for doing it. And who better to talk to about that than our Head of Earnings at the ONS Nicola White, how does the ONS find out what's on people's salary cheques every month. NICOLA WHITE We use several surveys to estimate wages. So, one is a monthly survey, which gives us the latest picture of what's happening, and the other is once a year, and this allows us to measure not only weekly earnings but also annual earnings, hourly earnings and it enables us to also look at detailed characteristics such as age, sex, region and occupation. It's a much richer data source. MILES FLETCHER Again, this is a big national level, thousands and thousands of people. NICOLA WHITE For the monthly survey, we ask to provide us with the number of employees in their business, and then what they're paying out in wages that month, and then we just calculate the average weekly earnings. The annual survey is slightly different. It's filled in again by businesses, but we ask for a selection of employees so that we can collect the additional data that we require. MILES FLETCHER So, we're not just trusting people to come clean about how much they're earning because I wonder if people might be concerned about what the tax authority might say. NICOLA WHITE As we collect this from businesses, we think the quality of the data might be much better than giving the individual data. MILES FLETCHER For statistical purposes, what is the average wage in the UK? NICOLA WHITE So, the average weekly earnings for all employees at the moment is around 565 pounds a week. Then if we include bonuses into this, it increases it to around 600 pounds a week. MILES FLETCHER And what's been the trend recently? NICOLA WHITE It's been quite difficult to interpret earnings recently given the pandemic, and one reason for is because COVID has impacted the workforce. So many workers were on furlough or had their hours reduced during 2020 and 2021. And this meant that people saw their earnings fall, pushing down weekly earnings, but in the following year, fewer people were on furlough and hours returned to normal, so then weekly wages were higher. Making that year-on-year comparison was quite difficult to interpret. And adding to that, the actual makeup of the workforce during 2020 and 2021 changed and because our statistics is an average this will impact on the average. During the pandemic we saw that lower paid people were at a greater risk of losing their jobs. So where fewer people were in the workforce, this increased average earnings. The way I like to think about it is as thinking about height. So, if the shortest person in the room leaves, the average height of those remaining will rise, but no one in that room has got taller, have they. It's just the makeup of the people in the room that has changed the average, so if you think about that in terms of earnings, if someone's paid less than the average earnings per week, they then lose their job. Other things being equal, average earnings will increase and this was quite prominent during 2020 and 2021. But we're now seeing things return to normal levels. MILES FLETCHER Shaking out that furlough effect, if you like. Compared to pre pandemic levels, how do we stand now? NICOLA WHITE So at the moment, we're seeing when we compare to pay for this time, the latest papers are 12 months ago, we're seeing increases in regular pay, and in total pay which is regular pay plus bonuses. And we're seeing some high bonuses that have been paid out, particularly in March this year when we normally get the bonus months. We're seeing levels we haven't really seen before . MILES FLETCHER And what's been driving that then? NICOLA WHITE The main sectors that are contributing to this is the finance and business services sector, and within here are financial and insurance activities. That's banking, it's not unusual for these sectors to see large bonus payments, and they're just continuing to be quite large, although we did see some smaller bonuses paid during the pandemic. We've then seen this rise to levels we haven't really seen before. MILES FLETCHER And how disproportionate is the effect of these city slickers getting Ferraris? NICOLA WHITE If you look at the data split by private sector and public sector, you'll see public sectors very minimal bonus payments there, whereas it is all being driven by the private sector, and in particular the finance and insurance activity sector. MILES FLETCHER Any other sectors in which people have been getting bonuses? NICOLA WHITE Yes so there are other sectors such as manufacturing and construction and wholesale and trade. They've also been seeing quite large bonuses, particularly in March. MILES FLETCHER And that's perhaps a reflection of the shortages of appropriately trained and skilled workers in those industries, and employers are having to shell out extra to get people in. NICOLA WHITE Yeah, so bonuses are a way of retaining staff, and that will not impact on basic pay. They were not included in pay rises, but it's a way to keep staff from moving on. MILES FLETCHER Overall then, of course real pay has suddenly become a talking point again. For years and years when inflation was relatively low it was a concept that wasn't discussed that much. Now inflation has gone back up and people are concerned about the real value of their earnings. Just talk us through how we measure that, and why it's so important. NICOLA WHITE Yes, we do produce a real average weekly earnings estimate which adjusts for inflation. So here we look at the growth rates of wages, and we then adjust this by the latest inflation rates. So as you've just said, inflation is currently very high, so it is having a big impact on real wage growth rates. Following the recent increases in inflation, pay has now clearly fallen in real terms, both including and excluding bonuses, so that's excluding bonuses. Real pay is now dropping faster than any time that we've seen since records began in 2001. MILES FLETCHER What's the benchmark for the rate of inflation that the ONS uses? NICOLA WHITE So, we use the CPIH version of inflation. And that's what we adjust our estimates by. MILES FLETCHER Because the ONS believes that's the most reliable? If we were to take RPI, which of course we don't recommend, the real base situation would look even more pronounced. NICOLA WHITE Inflation as measured by CPI, which at the moment is slightly higher than CPIH. This would have an even bigger impact on growth and real growth rates if we were to use CPI, which is often used by the Bank of England. MILES FLETCHER So Nic, another issue in recent years, of course, has been the gender pay gap, which we've heard a great deal and that's not, it's important to explain isn't it, it's not the difference between men and women getting different pay rates for doing the same work, because that's been illegal for some time. This is about women as a group being paid less than men as a group. How does the ONS measure that, and how have things been changing? NICOLE WHITE We use our annual survey to measure the gender pay gap, and what we do is we calculate the difference between the average hourly earnings of men and women as a proportion of men's average earnings. For example, we'd say that the gender pay gap currently is at 7.9%. What this means is that women earn 7.9% less on average than men. If we had a negative gender pay gap, for example, negative 4%, this would mean that women earn 4% more on average than men. As you just said, it's not a measure of the difference of the same job being paid. It's a measure across all jobs in the UK. MILES FLETCHER But that's all men, compared to all women. But if you start to break it down, then a slightly different pattern emerges, doesn't it? NICOLA WHITE Yeah, that's right. It's interesting to look at this by age group, because there's a clear difference for those aged over 40 and those aged under 40. With those full-time employees under 40, they have a gender pay gap of around 3%. And for those aged 40, this is around 12%. And this reflects the type of jobs and the fact that women have had children at that age. MILES FLETCHER So, it's those family responsibilities, taking people out of their careers? NICOLE WHITE And maybe working more part-time. It's very much at the younger ages when the gender pay gap isn't as big, but as you go into those older age groups it does become more prominent. MILES FLETCHER? And perhaps there is an occupational skills divide as well? NICOLE WHITE Yes, there is. So looking at 'occupay gap' in this gender pay gap, the biggest gap is for processing and machine operatives, which is at 16.2%. Women earn 16.2% less on average than men, which probably you'd expect because these jobs are generally held by men. But if we look at this at the other end of the scale, so we'll look at the largest negative gender pay gap. This is in the occupation of secretarial and related, where women earn 7.4% more on average than men. So, the occupations kind of tie in with the kind of jobs that men and women do tend to do. MILES FLETCHER If I knew someone for whom the world of statistics had just become too exciting and they had to go work in a less dynamic field, but were out to make a bit more money, what should I recommend they do? NICOLE WHITE Okay, for full time employees, the highest paid occupations are chief executives and senior officials, and they're paid around about 90,000 pounds per year. The lowest occupation for full-time employees is playworkers, which includes teaching assistants, child minders and nannies, and these are paid around 14,000 pounds per year. But if you want to look at all employees, the highest occupation is still the same group, which is chief executives and senior officials. But the lowest paid occupation changes here, and it's more school mid-day and crossing patrol occupations. And these have a medium of around 3000 pounds per year. And this is because much of these jobs are part-time. MILES FLETCHER So that's what's going on with pay. But what's the current situation with employment in the labour market overall then, suffice to say, David, it's complicated really, isn't it? DAVID FREEMAN A very accurate description, I think complicated or a very mixed picture at the moment. As we touched on earlier, there are a lot of people who removed themselves from the labour market and go into economic activity, particularly in the over 50s age group. So that means it's held all the unemployment down a bit. There's also a record number of vacancies, which you would normally say is good news, but it's been at a record high for quite a while, so over 1.3 million vacancies and that for the first time is slightly more than the number of unemployed people. So that means companies are struggling to fill the jobs that are available particularly in things like the health sector, hospitality and the retail sector. MILES FLETCHER So that's speaks of skill shortages then isn't it, employers need people, but they haven't got the right people. DAVID FREEMAN Yes, if you haven't got the right people, or not people in the right areas of the country, there's plenty of challenges there in trying to make sure that these jobs get filled and we find the right people in the right place. We're also seeing falling self-employment as well. This is the one area where we're still lagging behind where we were before the pandemic started. So the number of employees has reached its pre pandemic level, but the number of self-employed is over three quarters of a million below where it was before COVID-19 struck. So that's again another challenge. Where have these people gone? Have they gone into inactivity or employment or are they struggling to restart their business after the pandemic. MILES FLETCHER Is that perhaps because of the disruptive effects of the pandemic, when it was easier for a lot of people to take one of the many jobs that are available rather than to go back into self-employment with all the risks and uncertainty that then implies. DAVID FREEMAN Potentially we have seen lots of people moving into employment and leaving self-employment over the pandemic period. I mean particularly with a lot of jobs that are offering flexible hybrid working, people are finding it much more constant, a bit more reliable than perhaps they were in their self-employed jobs. And lots of jobs in self-employment would have been hit by the pandemic. There were lots of jobs in construction, in catering and in the service sector, which would have been hit by the pandemic. MILES FLETCHER We said the picture was complicated, but anytime where we have record high employment and a record number of vacancies, there's good in this labour market too isn't there. DAVID FREEMAN There is some good news, they say the number of employees is back above where it was pre pandemic, so a lot of people in employment. What's holding it back is the self-employed. And, the level of unemployment is one of the lowest we've seen since the mid 70s. It's down below 4%. So, there are very few people out-of-work actively seeking work. That again shows there's certainly scope for the labour market to expand with the number of unfilled vacancies that we're seeing. MILES FLETCHER On that largely positive note, it's back to the daily grind we go. Thanks to Nicola and to David for joining me, and thanks to you for listening. To comment on this podcast or ask us a question please follow us on Twitter at @ONSfocus. I'm Miles Fletcher and our producers at the ONS are Julia Short and Steve Milne.

In this episode Miles is joined by Dr James Tucker and Sarah Caul MBE to talk about how and why the Office for National Statistics count births and deaths, and what current fertility trends might mean for the future population. They look at the impact of popular culture on the most common baby names in England and Wales, and discuss the new significance of a dataset that was itself buried for 50 years. Transcript: MILES FLETCHER I'm Miles Fletcher and this episode of 'Statistically Speaking', the official ONS podcast, is literally a matter of life and death. Specifically how and why we count births and deaths and what those numbers are telling us. We'll talk about the possible impacts of declining fertility rates in the UK and of children being born to older parents. And at the other end of life we'll look at the new significance of a dataset that was itself almost buried for 50 years I'm joined here at ONS by two people who lead on all our data around births and deaths - Head of Analysis in our health and life events teams, James Tucker, and our very own Head of Mortality, Sarah Caul MBE, honoured for her work during the pandemic about which we will talk later. Starting with you then James, at the beginning as it were, with births - how does the ONS gather information about the number of children being born in England and Wales week in, week out? JAMES TUCKER So the registration of births is a service that's carried out by local registration services in partnership with the general register office in England and Wales and the good thing about this, from the perspective of having a really nice complete dataset, is that birth registrations are actually a legal requirement, giving us a really comprehensive picture of births in the countries. MF So we gather the numbers, we add them up, what do we do with the information then? JT So there's a couple of ways that we look at the data. One is to simply look at the number of births per year. So for example, we're looking at about 600,000 births per year at the moment. But an alternative approach is to use what we call the 'total fertility' rate, which is basically the average number of live children that women might expect to have during their childbearing lifespan. So it's a better measure than simply looking at the trends in the number of births because it accounts for changes in the size and age structure of the population. MF So it has a sort of multi-dimensional value then statistically that you can use to infer various things about the age at which people are likely to have children, and how many they're likely to have. JT That's exactly right. So we've seen some changes in the total fertility rate in recent years. So if you've heard the expression 2.4 children as describing the average number of children per family it's now considerably lower than that. In fact, it hit a record low in 2020 when the total fertility rate was 1.58. MF That's a sharp decline. In fact, though, you've got to go as far back as 1970, when the current series began, that's when it really was 2.4. What's really striking is if you look at that graph, the decline that happened between 1970 and about 1977 - very sharp decline there. Do we know what happened during that period? What were the factors driving that particularly? JT I think there can be all sorts of socio-economic factors affecting the fertility rate: improved access to contraception, reduction in mortality rates of children under five, which can result in women having fewer children. And also, more recently, as we've seen the average age of mothers going up, we might see some lower levels of fertility due to difficulties conceiving because of that postponement in childbearing. MF Sarah, I can see you want to come in on this. SARAH CAUL So my mother had three children by the time she was 30, and growing up I would just assume that that was the route I was going to take because it was what I've known. I am now 31 and I think if I was pregnant, that thought would scare me. I don't think I've grown up enough to have a child. I'm a dog mum, but those don't come into the statistics. MF So there was a bit of fanciful talk about people in lockdown finding - how should we put it delicately? - you know, things to do with their time, and that might lead to a boom in births. But that didn't really transpire? JT The increase in 2021 would actually coincide with conceptions across the second and third lockdowns. So yes, there was some speculation that people may have had enough of board games and were occupying their times in other ways, but I think it's actually more likely that it's a result of people delaying having children earlier on in the pandemic because of the uncertainty that was around at that point. And then towards the end of 2020 people had moved on from that and we saw a bit of an increase. MF Nonetheless though, historic data shows that there is a most common time of the year for conceptions to take place and that has something to do with the festive period, doesn't it? JT That's right. So the most common birthday is generally - almost always in fact - towards the end of September. So it doesn't take a statistician to work out that means the most popular time to conceive is over the Christmas and New Year periods. So that could be due to the Christmas festivities, but it might be also be something a bit less romantic than that. Some people, for example, might consider that there's an advantage to children being older in their year in school for example. MF The ONS also publishes the list of most popular baby names every year, and it is apparently one of the most downloaded and most popular bits of content on the ONS website. James, a lot of people scoff at this as an exercise. Is there any value in this list of baby names? Or is it something the ONS just produces because people like it? JT As you say it is one of our most popular releases and I think people use it to inform their own choices of names, and it can also tell us some really interesting things about culture in the country at the time. The top of the league table hasn't been that interesting, to be honest. So Oliver and Olivia have been the most popular names for the last few years, but it's beneath that that there's some really interesting trends emerging. So there's always a lot of interesting names that are going extinct. For example, last year, it was picked up a lot in the press about the name Nigel, which joined the list of critically endangered names like Gordon, Carol and Cheryl, and we do also see some really interesting influences of popular culture. And also royal babies always have a big influence. Some of the interesting ones from the last few years - we've seen some more Maeves and Otis', which are characters from the TV series 'Sex Education', and even some Lucifers from the series of the same name. But generally you'd expect there to be positive associations with baby names so you do almost always see an influence of royal babies - we've already seen that with George but might be predicting a rise in Archies with Prince Harry's son. MF And it's quite interesting, seeing the cyclical thing with names that you might have associated with previous generations coming back into popularity, and Archie is a great example of that, isn't it? Sarah was one of the most popular girls names for a long time, certainly in the 80s and the 90s. But Sarah it's dropped out of the top 100 altogether. SC It has dropped down, but there's a Sarah in every single generation in my family. I think we're all named after each other. So my family is doing its best to keep it alive. JT Just a bit of a question for you. Where would you put the name Miles in the ranking? MF Well, it's probably not in the top 100 James. JT Yeah, I'm afraid it's not quite top 100 material, but it is number 144. There were 390 Miles in 2020. And it's actually been on a bit of a roll recently. So that's the highest ranked it's been since 2002. MF Perhaps it's the growing popularity of this podcast James, or maybe something else at work. Anyway... One thing worth noting about this before we move on, it should be pointed out that producing the baby names list is not an expensive exercise for the ONS. JT No, the data is very straightforward to collect. It's just a matter of compiling it into something that can be easily accessible and interesting for people to look at. MF And it's also one of the reasons that we don't compare the spelling of different names, because there's this long running thing isn't there about how if you added up the different spellings of the name Muhammad, then that would be the most popular boys name in England. That's not something the ONS does because, quite simply, we're just seeing the spelling that people enter on the system. JT Yeah, that's exactly right. And I think increasingly that could become even more of a task to compile those, because we're seeing an increasing use of shortened versions of names or alternative spellings. And if we were to try to compile those into one then that would definitely increase the time that we spent on it. MF Well, there you are, everything you need to know about baby names and - more seriously - the measurement of births and fertility. Plenty more information of course on the ONS website. With that, we must turn to the other end of life, and that is measuring deaths - a topic which has been very much in the news for the last couple of years since the outbreak of the pandemic. Right at the centre of that has been my colleague Sarah Caul, who's sat with us this afternoon. Sarah, you're recognised for your achievements during that period with an MBE, official honour, which you collected from Windsor Castle. SC It was definitely very surprising. I wasn't expecting it, but I'm very thankful for it. It's quite a proud moment in my life. If you ever see my mum, she'll just scream at you: "My daughter's got an MBE", so that's always nice. MF Recognised now then as an authority in this area - it's fair to say that the ONS was publishing this list of weekly deaths very quietly, almost unnoticed, for many years. And then of course, sadly, that changed at the start of the pandemic. SC With 'weekly deaths' it did have a small audience, to the point where they were considering actually not publishing it anymore. Pre-pandemic it wasn't a very large part of my job, because it was just something very quick and easy to do. My main analysis would be on annual data - we release annual data the summer after the end of the reference period. We would look at different causes of death and see where we could investigate further to help monitor the picture of what people are dying from, and if that can be prevented. MF That all changed of course March / April 2020 with the arrival of COVID-19. SC We started quite early thinking of what we could do with COVID and we added just one line into the spreadsheet, which was the number of deaths. It went from something like five to over 100 in one week and we were like "okay, we have to do a lot more of this now". It just grew bigger and bigger because we were having more and more deaths and we needed to get out, as quick as possible, as much information as we could. We would be doing something that would usually take us months to do in a matter of days, every week. And we're actually still doing it to the same level now because we are still seeing COVID death - it hasn't completely gone away. MF Incredible demand for information from government, from everybody, of course - desperately concerned about what was happening. There was suddenly this incredible focus and attention, and huge pressure, on you to get those numbers out very quickly. SC Those first few months were quite a blur, because we were publishing weekly and monthly and were constantly adapting and constantly trying to figure out what people were interested in seeing. And getting that information out into the public domain is probably the most challenging time that I've had here. I don't think I've ever worked at that pace before. But we have got so many experts in the health analysis and life events area that we're in. We had expert coders, experts in different causes of death. It was great to see everybody come together and work really well together. Despite the enormous amount of pressure, we were having to deliver things that would normally take us months in days, and sometimes hours. MF Your team were actually among the first to see the full impact, because there wasn't so much testing going on among people who have been infected. And it was in those mortality figures that the real impact was first being revealed. SC It wasn't until our death certificate information came out, because testing was so limited in the early days, that you could kind of see the impact, and see how quickly it was increasing. MF How do we gather those numbers? SC So when somebody dies, the informant - or family member usually - will register the death, usually within five days, but depending on if it needs to go to a coroner, it could take months or even years to register that death. And we don't know about a death until it is registered. When that information gets put through all of the causes of death listed on the death certificate comes through to us at the same time with an assigned underlying cause of death, as well as contributory cause of death. So we have all of that information on each and every death registered in England and Wales. MF And it's very important to understand you can have more than one cause of death because this is very relevant to understanding how many people might actually have died because of COVID. SC The majority of deaths, regardless of cause, have more than one cause listed on the death certificate because you have complications, and one cause could lead to another cause. So the way we categorise it is deaths 'due to' COVID - where COVID was the underlying cause of death or any other condition - and then deaths 'involving' it - so where it was mentioned on the death certificate as the underlying cause or a contributory factor. MF Do you think a lot of people were actually confused by that? SC One of the things that people struggled to understand sometimes during the pandemic was that this is a different number to the public health measure. So somebody could test positive for COVID-19 but not have COVID-19 on the death certificate, because it didn't contribute to the death. So the example that gets told quite a lot is if somebody tests positive and then gets hit by a bus, it's very unlikely that COVID will be mentioned on the death certificate. MF And that's absolutely vital in understanding how many people have died 'from' COVID as opposed to a death 'involving' COVID. SC Yeah, so it's very important. The public health measure's great because it's really fast, and it gives us a more instant knowledge of what's happening. Our statistics come out about 11 days later, but it's where COVID contributed to the death, and not just was present time of death MF That helps us to really understand what the mortality impact of COVID-19 has been so far. SC It is really important. So from the start of the pandemic to the week ending 13th of May, we know there's about 195,000 death certificates that had COVID on them, and that's the whole UK as we've worked with colleagues in Northern Ireland and Scotland to bring a UK figure together, as usually we only report on England and Wales. And then that enabled us to do further investigations about who was most at risk of dying from COVID. And we did a lot by age, place of death and any breakdowns we thought possible to try and help identify those most at risk. MF Another great strength you might say of the ONS numbers is the comprehensive nature of the way the information is gathered centrally and reported very quickly. And that was evident during the pandemic when you saw the UK numbers coming along and influencing policy decisions really quite rapidly, compared to similar countries around the world. Central to that is the whole concept of 'excess deaths'. That's a good objective measure of impact, regardless of what doctors have written on the death certificate. Sarah, tell us how that works, particularly what is its statistical value, and what's it been saying? SC We use 'excess deaths', which is the number of deaths we see in a period compared to what we would expect - and to get the expected number we use an average of the previous five years. By doing this, it takes into account the direct and indirect impact of COVID, so we have a fuller measure. It's really useful as well for international comparisons, because we're not relying on everybody recording deaths in the same way. It's just a straightforward "how many deaths above what we would expect are we seeing?" MF And what has it shown so far - what has been the impact on excess deaths? SC So we've seen quite a high number of excess deaths during the pandemic. In 2020, we saw over 75,000 more deaths than we were expecting originally. In 2021 that is lower - we saw around 54,000 deaths more than we'd expect. And currently to date for 2022 we are seeing the number of deaths slightly below what we'd expect looking at our five year average. MF Do we know yet - at the least the early indications - for what this might all mean for life expectancy? SC We have released some life expectancy statistics for 2018 to 2020 as we do three-year combined, and we do see a bit of a dip in the last year because of the high number of deaths in 2020, which was due to the pandemic. We're still seeing the numbers are significantly higher than at the start of our time period, which was 2001 to 2003. Somebody in England in 2018 to 2020 would live to about 79 years as a male, or 83 years as a female. Whereas in 2001 to 2003 it was more like 76 years old for males and 81 years old for females. MF So in recent history we've seen these really quite pronounced increases in life expectancy for men and women. SC People are living longer. It's increased more for males than it has for females. It's reducing that inequality gap, because we do see that women do tend to live longer. MF Do we know why men are catching up with women in terms of life expectancy? Is it lifestyle, nature of work perhaps? SC There is a lot more of a decline in heart diseases, and especially in males, so I think that could indicate healthier choices, which would then increase somebody's life expectancy. MF Another important concept when understanding how the ONS looks at mortalities is the whole question of 'avoidable deaths'. So how does that work and what is it been telling us? SC So 'avoidable mortality' is defined as a cause of death that is either preventable - so for example COVID and appendicitis is included in this – or are treatable - so this would be different types of cancer. For those aged under 75 in 2020, 22.8% of all deaths in Great Britain were considered avoidable. This is around 153,000 deaths out of 672,000. The categories where we've seen the biggest increase since the start of our time series was alcohol and drug related disorders, which is the only group of causes where the mortality rate is significantly higher in 2020 when compared to 2001. But the biggest driver of avoidable mortality would be the cancers. MF So those figures for avoidable death might suggest then that there is still considerable disparity in life expectancy between different groups. SC So we see through our data that those living in the most deprived areas have a substantially higher rate of death from avoidable causes - with deaths due to COVID-19, drugs and alcohol being notably higher in the most deprived areas. Avoidable deaths accounted for 40% of all male deaths in the most deprived areas of England, compared to 18% in the least deprived areas in 2020. And then we see the difference again for females. It was 27% of deaths in 2020 in the most deprived areas, and then 12% in the least deprived areas. So this gap in avoidable mortality between the most and least deprived areas - it's actually at its highest level since 2004 for males, and since the data began in 2001 for females. MF James what are the factors that are driving those disparities which are, on the face of it, pretty serious? JT The difference between the most and least deprived areas is one of the most striking statistics we produce actually. And I think it really shows the importance of looking beyond those top level figures. And that's the ability we have here to look at the minute detail of the data. I mean, there's all sorts of factors that can go into life expectancy. So there are things like access to health care, nutritional aspects - there's plenty of things that can drive that gap, but it's really, really striking and definitely needs looking into. MF What's the direction of our work in this area? Because for some areas are we not seeing actually a sustained reversal of life expectancy, not just shorter life expectancy, but one that's actually getting shorter. JT I think you mentioned earlier Miles about how this mortality data had kind of risen from obscurity I think. During the COVID pandemic the spotlight has been shone on deaths and Coronavirus itself, but really there's going to be a period where we're really going to have to make best use of that data to look at the indirect effects of Coronavirus as well. So, take for example just within the pandemic we saw a big increase in alcohol related deaths in 2020, and that tallies with other research that shows that patterns of drinking have changed during that time with heavy drinkers drinking more. So beyond the pandemic as well - we're looking at things like delays to treatment times for certain diseases. So there's plenty of analysis still to do on the impacts of the pandemic. MF Deep in the recesses of the ONS data though, the causes of deaths that are recorded - some of them are, you have to say, they're unusual, they're quite remarkable. Sarah, can you give me some examples of some of the most unusual deaths that have been recorded? SC So I've got a few of the least common causes of death, and I don't want to scare anyone - the numbers that I've got here are over an eight year period, so they're very rare. So I don't know if you want to see if you can take a guess at how many people are 'bitten or stung by non venomous insects and other non venomous arthropods'? MF People attacked by bees and wasps, that kind of thing. SC Not because they're venomous, but because of the incident themselves. MF Well I'd like to think there was a very small number. I don't know - over an eight year period - hopefully less than 50 or so? SC It was less than 50. It was 12 - which is more than I was expected. Another one we have is 'fall involving ice skates, skis, roller skates, or skateboards'? MF Can be very dangerous. I don't know, 5? SC Three! Very good guess. I for some reason thought it would be more than being bitten or stung by an insect. We've got 'victim of lightning'? MF Rare again. Highly unusual. I don't know... 10? SC Seven! You're quite good at the guesses. I'm very impressed. MF You know, you hang around the ONS long enough and you start to get a feel for these things. What do we think is the most unusual cause of death that we've recorded? SC We've got a lot that only have one death. One of the ones that springs to mind is 'bitten by rat'. I did expect more people to die from that than some of the other ones we've got, like 'contact with powered lawnmower'. But I guess that's quite a dangerous thing to do, especially if you're like me and start doing it in your flip flops. So yeah, dangerous. MF Definitely not recommended. So we've looked at births and we've looked at deaths. But what's the balance between the two at the moment, James, and what's the impact on our population of all this overall? JT Population change is driven by the number of live births and the number of deaths and the balance between those, but also the migration that takes place each year. So the difference between the number of births and the number of deaths is a component known as 'natural change'. Over the last decade or so, although we've generally seen more births than deaths, we've actually seen a narrowing of the gap. So all else being equal, that means that the population growth will slow. Also, we did actually see a blip in 2020 when for the first time for a while the deaths exceeded births, but that's going to be due to the very high number of deaths that we sadly had from Coronavirus in that year. MF And that was highly unusual - the first time in many years we've seen that. JT Yes, that's right. So the general trend has been more births than deaths and we've seen a return to that in 2021. MF Well, there we are, proof that the ONS really does cover us from the cradle to the grave. 'Statistically Speaking' comes to you from the Office for National Statistics. I'm Miles Fletcher, thank you very much for listening. Join us for the next episode, which you can hear by subscribing to this podcast on Spotify, Apple podcasts and all the other major podcast platforms. Our producers at the ONS are Julia Short, and Steve Milne. ENDS

Our topic this time, and it's a big one, is the economy. The science of measuring rapid change in a complex, globalised and now increasingly turbulent economic situation. In this episode Miles is joined by second permanent secretary Sam Beckett, and head of inflation, Mike Hardie, to look at how the ONS is keeping on top of rising prices, and how two of the biggest economic shocks in recent history have helped shape the Office for National Statistics' (ONS) current approach to collecting its key economic data. TRANSCRIPT: Miles Fletcher Sam, one angle I'd like to explore with you is the extent to which everything has changed recently, and the way that the ONS measures the UK economy, the extent to which that was informed by the experience of what happened 14 years ago now and the financial crisis. Could you talk us through what happened there in terms of the ability of the statistical system to actually spot what was going on? And what lessons were learned during that period? Sam Beckett Yes, certainly. That is going back quite a while now, isn't it? But I think one of the key things that you can really compare and contrast with where we are now compared to then, is about the timeliness of GDP. Back at the time of the global financial crisis the Office for National Statistics was very slow to spot the turning point. We were dealing with crucial data for the economy's output. And it was probably about six months before we were able to sort of scale the downturn in the economy and see the economy going into recession. MF Meanwhile, during that period, of course, people were being hit quite badly by that economic downturn. But the official statistics that were available had nothing to say about what was happening. SB No, that's right. So we would have been waiting to find out the extent of the downturn as people were seeing it hit their livelihoods, for something like six months back in 2008. If you fast forward then to the experience that we've had over the pandemic. You know, our monthly GDP statistics are out about six weeks after the period they refer to so you're getting a very timely indicator on what is happening to the real economy now. So you can really compare a sort of six months gap to a six weeks gap now. And if you think about the way the pandemic played out with, you know, the economy being closed down to try and limit transmission and then opened up again successively, and in the waves, if we'd been waiting three months or six months to find out what was happening, it really would have been a hopeless situation. But we got those very timely official statistics on GDP, but not only those but even more timely statistics from business surveys, and opinions and lifestyle surveys that we've done, where we can actually get a two week turnaround on what is happening to the economy and how people are responding. MF So it was really a question of learning from that experience and putting in place the kind of mechanisms that can help us as a country to actually find out what was going on closer to the point it was actually happening out there in the real world. Has the rest of the world learned that lesson as well, or is the UK among countries that have been quicker onto this do you think? SB We're certainly one of only a handful of countries that publish a monthly GDP figure. So I think in that big kind of headline and official statistic, we're still in a relatively select group that publish as frequently as monthly and as close to the time. We're also looking at financial card transactions data; we are looking a lot at admin data on the labour force, and trying to bring together a host of statistics that shine a light on what is going on, on the ground during the economy. And I think we count ourselves amongst a relatively small group of national statistical institutes that are cutting edge in their use of innovative data sources. MF So by the time the pandemic then comes along, two years ago now, the ONS is in a better state to actually find out what's happening, but nevertheless, was there a certain extent to which the organisation had prepared for another downturn like 2008, rather than what actually happened which nobody had foreseen, a widespread pandemic including a serious risk to life? SB Indeed, I mean, who would have thought that you know, we would have been hit by a pandemic of such a global scale and impact? I think one of the things that is a huge advantage for the government and the UK economy has been to have this objective handle on the level of infection out in the community. And that is something that the Office for National Statistics signed up to deliver really early on in the pandemic. So, our COVID infection survey, which has now swabbed millions of people on their doorstep, gave us a great handle on just how many people have had COVID, not just relying on the data of people who were turning up at doctors and hospitals, who had symptoms already. So you know, the COVID infection survey was a more random sample of the community and gave us that objective handle on how many people had COVID and indeed, some of them asymptomatic, you know, no symptoms of COVID but tested positive on the doorstep and that gave us a great insight over the pandemic and helped advise the government on what should be done to try and limit transmission. MF So meanwhile, as well as setting up that very important survey, there were a lot of other very quick changes that were put in place as well to measure the economic impact, the impact on individuals, on businesses as well. Can you talk us through some of the work that was done there to give that very quick turnaround, the fast indicators, that quick view of how items in the shops are being affected; how people in the workforce were being affected; and how the country and the effects of lockdown - to what extent they were actually hitting the economy in real time? SB I mean, starting with those quick turnaround surveys, there's two really that are really good companions to each other. The first is the business insights and conditions survey - and that surveys about 40,000 businesses and asks them questions around, you know, what is happening to their customer base, what is happening to their workforce. And there's about a two-week turnaround on that information. So, we could ask questions of businesses about how many of their staff, for example, they were intending to put on furlough and get that information just two weeks later to give us a handle on what a big uptake there would be on that scheme. The companion one is the opinions and lifestyle survey and through that we were able to ask people things like were they wearing a mask when they went to the shops? You know, were they staying at home as per the guidance and what were they leaving the home to do? And you know, were they washing their hands more and all those non pharmaceutical interventions that were so important in controlling the early stages of the pandemic. And again, between that sort of survey of households and individuals and businesses, you could track those two sides of how the pandemic and the government's measures to control it were impacting on people's lives and livelihoods. MF So in the old world of statistics, where paper forms would have been sent off, we'd have been able to produce an estimate in, ooh I don't know, a couple of months. But actually with the onset of the pandemic, this information was being fed into government, directly into government within a matter of a few days and informing that response, the actual action that was being taken on the ground. SB Absolutely. And I think also looking at some of our more traditional statistics, there had to be huge effort to keep the show on the road. Labour market statistics, I mean, incredibly important, over a period of economic turbulence, we had to go from what had been a face to face survey to a telephone based survey. And we reinforced that picture by getting information from payrolls from HMRC's PAYE database, to understand what was happening to the labour market and keep that total picture, even though our standard survey had to move rapidly to a telephone based one. But I should add, you know, when people think about that admin data, I would like to emphasise that we're incredibly careful that none of that would identify anything about individuals. And we're extremely careful to ensure that we don't collect data that we don't need and that everything is de-identified. MF And that's a very important point now, because it's not just a question of people taking part in surveys is it? It's about the ONS having relationships with the credit card companies, for example, with mobile phone providers as well. And while these huge datasets give a fantastic up to the minute picture of of what's going on - money being spent and how movement is being affected as well - people are going to be understandably concerned about government having access to that sort of data. So how do we ensure that that is working in the public interest, only producing information that's genuinely needed for the public good? SB Our reputation rides on treating people's data incredibly carefully, and by abiding by all the regulations that are appropriate to personal data and business data. So we're incredibly scrupulous and careful in this regard. We don't gather data that can identify people if it is not needed, and we have got very reliable methods to de-identify data before we use it for analysis or indeed publish it. So you know, that's incredibly important to maintaining public trust in our statistics. MF So what have we been doing to try and measure the individual impacts that some of the price rises we've seen recently have had on households with different incomes? SB We are facing a period of some time to come where I think this is going to be incredibly high profile in the public debate about the challenges of the economy and what people are facing and indeed of measurement for us as an office of statistics. What we've been doing is trying to think about ways in which you can dig under that very average national figure of inflation. Now that is going up and most forecasters, such as the Bank of England will expect it to go up further, but it does, as you say, fail to show how different people can be impacted. You know, if they drive a lot and the cost of fuel has gone up a lot, relatively poor households spend a high proportion of their money on energy bills and on food and we know that both of those categories have been affected. So we have published some statistics that seek to look at inflation cut by different income brackets of households. MF Given that there is now so much data from supermarket scanners, from credit cards, from an incredible range of digital sources. What are the limits of all this do you think? SB Data is a by-product of the productive economy these days, isn't it? You know, data is being produced in all the other activities that we undertake online in our lives. So along with that, computing power has got so much cheaper and you put those two things together, and you just have this enormous capacity to measure activity in so many different ways, and so much more up to date, I mean, compared to anything we could have done, instead of 10 years ago, or 20 years ago, and the cost of them has come down massively. And with that, the sort of potential to get insight from them has expanded. MF Now we've mentioned GDP several times of course – that's Gross Domestic Product - the traditional very long-established way of measuring activity in the economy. And it's held by many still to be the single most important national economic statistic. But at the same time, there's a debate going on at the moment about the continuing usefulness and relevance of GDP, particularly as it takes no account of the environmental dimension as well. And of course, in this country and internationally, that environmental dimension and climate change has become evermore important. So what are we doing as an organisation to factor the environment into the economic picture? SB GDP is an important measure of the productive economy. I think it's here to stay. But even in terms of it measuring the productive economy we're continually trying to improve its quality and make it more timely as we've talked about, but also more granular, you know, get more of a sense of what is happening down at a more granular level of geography. What we're trying to do is develop further, all aspects of our kind of economic welfare measures and bring things into the kind of spotlight that GDP has that are really important to all our futures. And I think, you know, climate and net zero, and those environmental statistics are one area where we're working really hard to try and give them a due prominence. I mean, we are relatively far ahead of international averages in terms of our level of development here. We've been publishing natural capital accounts for some 10 years. So we're starting from a good base, but there's so much more we can do. So, we've got two strands of work here. First, we've got an approach which tries to extend that concept of GDP, the production and asset boundaries that it measures to natural capital in the environment, as you've mentioned, but also human capital, as well. You know, the extent to which the skills of the UK workforce are being enhanced, and other aspects of economic activity, which currently fall outside of GDP, like household production, like unpaid for household work, which also really ought to be in your concept of how productive you are as an economy. So, we're developing this suite of measures that sort of extends the national accounts into these harder to measure areas that we also know are really important to our sense of economic progress and prosperity as a nation. And so that's that sort of integrated set of extending the concept of GDP to these broader concepts. But also, alongside that, we are doing some things that are a little bit more tactical and fleet of foot. They have a framework to them, like our Climate Statistics Portal, but that brings together all kinds of climate statistics from across government into a kind of one stop shop for users to explore things like climate and weather and emissions by different area, impacts and mitigations and provide insights from that. Now, not in a way that you can really aggregate with the GDP number, but in a way that would give you sort of broad insight as to progress towards net zero and what is happening to our climate and weather. So, this is a huge agenda. We call it the 'Beyond GDP' agenda, something where we are a relatively leading internationally but so much more work that we can do. We've got some really interesting stuff coming out later this month that will look at some of these issues and you can obviously catch up with that on our website. MF So much more change still to come. Finally, Sam Beckett, a very wise economist once said - slightly tongue in cheek – that the chief function of economic forecasting is to make astrology seem respectable. Do you think the point will come at ONS when the data becomes so good and so rapid, that actually the ONS could get into the whole business of forecasting the economy with a great deal of accuracy? SB Well, I think we are increasingly getting up to the moment, if I can put it like that in terms of our economic statistics. Yes, there's still some time lag between the observation and the publication of the data in in most cases, but we're getting closer and closer. And we are using techniques where even where some data might be missing, we can use sophisticated economic modelling techniques to bring it up to date. So, a good example there would be if we didn't have a full local breakdown of GDP data for last month, we could make up for that using what we know about the other areas, and how they changed in GDP, and also the past performance of the missing areas. So, we can put together this picture that brings things really up to date using some of those modern techniques. I think the world of measurement is different from the world of forecasting, quite fundamentally. And, you know, we leave that to colleagues at the Office for Budget Responsibility and the Bank of England, who do kind of look ahead and try and paint that future picture. But the two are interconnected. And I think you can only produce good forecasts, if you've got really reliable readings on what is happening now and what past trends have been. So, they are hand in glove and I wouldn't want to say those were two distinct but we do have our own particular objective, which is about you know, economic and societal measurement. We're not yet in that forecasting game. But we are bringing it as up to the minute as possible. MF So, while not actually trying to predict the future, at least we can measure the very, very recent past. Sam, thank you very much for speaking to me. Now, after decades of relatively low inflation, rising prices are back in the news. Tracking the impact of that on households is of course, vitally important work and at the ONS, that's the responsibility of the head of inflation, Mike Hardie. Well, Mike, anyone who follows the news and particularly recently with concern about the rising cost of living will understand the importance of inflation. But there are lots of different measures of it. Can you talk us through the different ways in which ONS measures inflation, and why each of them is significant? Mike Hardie So we have a range of inflation measures. The first family of statistics are consumer price statistics. And so we have the consumer prices index which most people will be familiar with and the consumer prices index including owner occupied housing costs, and they are our macro economic measures of inflation that are based on economic principles. We also have a second group of statistics which are called the household cost indices, and they are specifically designed to measure the changing costs and prices faced by different household groups. And that completes our family a consumer price statistics. And then beyond those, we produce business prices. So those measure what we describe as output or 'factory gate' prices. So those are the prices of goods leaving the factory gate and we also produce input prices as well. So all of the component parts that are used in the production process to produce a final product, how the price of those has changed over time, too. And that completes our business statistics. And then beyond that, we also produce house prices as well, which is very topical at the moment given the buoyant housing market in the UK. MF And underlying all those different measures of inflation is a very large data gathering operation. Now, there's a lot of change going on in that area at the moment, but first of all, describe for us how this traditionally has been done. MH Traditionally, in order to produce our consumer price statistics, we have sent price collectors out across the UK. We have over 300 price collectors, they go to over 140 different locations in the UK, with mini clipboards, and they go into stores and they price a range of different items. So at the start of the year, we construct a large shopping basket, a virtual shopping basket, which is based on what UK consumers spend their money on. And there's a list of approximately 700 different items. And we send the price collectors out to collect information on those items. And we also have some collection within the ONS as well. So we have a couple of teams that go online and collect a wide range of prices too. We also have some admin data as well. So for example, we get admin data on how the price of insurance has changed. And then we aggregate all of that data together to construct our consumer price statistics. MF Rail fares of course are always a big driver of inflation as well. Where does that come from at the moment? MH So that comes directly from the uplift that consumers face every year. So, when rail fares are increased on an annual basis, we capture that increase in our inflation measures. But one of the developments that we're actually undertaking at the moment is to move to using data from the rail delivery group. So that's essentially a census of all rail journeys in the UK. So, it gives us a much more detailed picture of how rail prices are changing across the country. MF So, we have groups of people out with clipboards, moving up and down the aisles in the supermarket; people looking at the web; some companies like rail companies, obviously providing information about their fares. But was that sufficient to provide a really good accurate measure of inflation or was it felt that there was much more that can be done MH So, it was sufficient to provide a high -level accurate measure of inflation. These are economy wide averages that we publish on a monthly basis. We're moving away from the manual collection that I described, where we send price collectors out into stores, where we are working with a number of leading retailers to get access to their electronic point of sale data. So, whenever you go to a supermarket for example, and spend money on your weekly shop, that information is captured by the retailer. We have a number of partnerships in place. Co-Op are one of the retailers that are happy to be named, where we get information directly from their supermarket tills directly to our systems at ONS, and we can use that data then instead of sending people into stores to compile our inflation estimates. And that data is extremely detailed. So, when we send people into store obviously there's cost implication to that. And they collect prices of narrowly defined items. So, they may for example, go in to collect the price of a loaf of bread off the shelf - we try to price the most commonly available item. What the electronic point of sale data will give us is a census of all of the prices within that store, and more importantly, not just the prices, but how much of each product have been purchased by consumers. So that fixed basket approach that I mentioned, where we set the basket at the start of the year, that will change likely for areas of the basket where we're using these new data sources, because it'll essentially be a dynamic basket that updates every month because we will have a summary of what consumers are spending their money on in real time which is really exciting. MF That's a real step change in approach then. How does the UK compare - are other countries doing this, moving away from the traditional approach into this much more dynamic and data driven way of setting inflation? MH It's the general direction of travel. So other National Statistics Institute such as the Netherlands and Australia have been doing this. It's really difficult to do, because utilising those new data sources such as scanner data requires the development of new methods, and also new systems as well. So just to give you an idea of the size of some of these data sources. We currently use around 200,000 price quotes to compile our consumer price statistics every month at the moment. And it's likely we'll be moving to several hundreds of millions of prices every month. So, we need to change our systems in order to manage the sheer size of the data essentially. MF This really is big data in action. MH It is really exciting and gives you additional insights into changing consumer spending patterns and how prices are evolving across the UK economy. MF Does that mean the annual updating of the basket of goods - which is always quite a popular occasion as we look to see what's in and what's out - is that going to go then? MH Not in the short term. So, there are specific areas of the basket that we're targeting with these new data sources. I've mentioned groceries, we've also touched on rail fares already and also used cars. But for the remainder of the basket, we will use traditionally collected data, so sending people out into stores and data that we've received directly and collect at ONS. So, we will still need to update that basket to reflect wider consumer spending patterns. Also, if you think about groceries, we have these new data sources for larger retailers. But in order to ensure that our statistics remain representative of price changes in the economy, we also need to capture prices from smaller retailers as well. Some of them won't have the facilities to provide us with data - so there will still be an element of manual collection. MF Now all this change - and very exciting change too - comes at a time of heightened concern about the rising cost of living and also the frequently expressed opinion that what appears to be the headline rate of inflation doesn't actually reflect people's own experience of rising prices that they face, particularly recently in the supermarket. How has the ONS been responding to that? MH So, the inflation measures that most people are familiar with such as the consumer price index is an average and when you dig into that average there will be some variation. So, everyone has their own personal rate of inflation depending on what you spend your money on. So, in terms of how we responded as an organisation, you can go on to the ONS website, and use our personal inflation calculator and outline what you were spending your money on every month. And based on that spending pattern we can work out your personal rate of inflation and how that compares to the headline. We're also undertaking some work on a set of measures called the household cost indices. And these are designed to measure the changing costs and prices faced by different household groups. So, you can break down those statistics into income decile you can break them down to expenditure decile, households with or without pensioners, and with or without children. So, you can see how changing prices and costs are affecting different household groups. And another piece of work that we're doing at the moment that's particularly interesting is we are aiming to publish over the next month a low cost index. So, this has been widely covered in the media, where some consumers who purchase value brands in supermarkets are being forced to move to more expensive brands because those value brands are no longer available. So, what we are looking at is for the price of those lower priced products when people are forced to move to higher priced products, what that means for price changes and the implications for the household budget on a weekly basis. So that's another piece of work that we're doing to provide further insights into the recent rise in the cost of living and how that's impacting different groups of people. MF And that could shed important light on people's actual experience of shopping when they find out that the cheap packet of pasta they used to buy simply isn't there anymore. MH Yeah, so one of the fundamental principles of a price index is that we control for quantity and quality changes over time, because we want to isolate that price change. So, what you've just described there wouldn't necessarily be captured by a price index, but it obviously has implications for people in terms of the household budget. So, we're looking at producing, you know, a range of supplementary statistics to complement our headline measures of inflation, to provide insights into these types of changes, which are having an impact on people's household budget. MF Now one of the big debates, one of the big issues surrounding the measurement of inflation in recent years, has of course been the retail prices index. Tell us a little bit about that - the criticisms of the RPI as a statistic, as a measure of inflation, and how ONS has responded to that. MH So we currently produce the retail prices index as a legacy measure of inflation. Our position on this statistic has been clear for some time. We think it is a poor measure of inflation, that tends to over or underestimate inflation. And we don't think it has the potential to become a good measure either. And if you were to address all of the shortcomings of the retail prices index, you move close to our headline measure of inflation, which is the CPIH, which is the consumer prices index including owner occupiers housing costs. So, we made a proposal to bring the data sources and methods from the CPIH into the RPI and that is due to take place in 2030. But we only produce it currently as a legacy measure as we acknowledge as an organisation that it is used for a wide variety of purposes across the economy. MF So, we've had the CPI measure of inflation for quite some time. It's very important of course, it's used by the Bank of England to target the reduction of inflation. It's also used very widely around Europe. But it doesn't include that measure of housing costs. Why is it so important to include housing costs as an element? What are the challenges of measuring that given that some people live in their own houses and other people rent them? That's the problem isn't it - trying to measure how those costs are changing for different people. MH It's a large part of people's expenditure every month. So, it's essential that it is reflected in our inflation measures. It's conceptually quite challenging to measure. So, we use an approach called rental equivalence and we use rental prices as a proxy for owning and maintaining and living in your own home. And we have very detailed information for the valuation office agency, which we use to compile our measure of owner occupiers housing costs. MF And that comes up essentially within a notional figure of what it would cost you to rent your own home. MH Essentially, and this is the direction of travel internationally as well. So other NSIs are moving towards using a measure including owner occupiers housing costs. At the moment, the consumer prices index is the Bank of England's inflation target and is widely covered in the media every month, but our aim in the medium term is to move our stakeholders towards using the CPI. MF Looking into the future then, a lot of exciting changes going on. And we continue to report inflation on a monthly basis. Can you see the time when perhaps there might be a more frequent reporting of inflation, perhaps even coming down to weekly or even daily? MH That is possible with the new data sources - we could produce more timely estimates. Producing our inflation statistics on a monthly basis is really challenging. It's quite a tight timetable, you know, to send price collectors out to bring in all admin data sources, and in future, the scanner data that we've discussed, as well. So, there's quite a tight turnaround. So, it's very likely that CPI and CPIH will continue to be produced on a monthly basis, but it is possible that we could produce supplementary statistics that are maybe more timely, but our focus at the moment is improving our headline measures of inflation. MF Inflation in the news, as it hasn't been for many years at the moment - you must be very conscious of the impact that your numbers have when they come out. Describe for us the importance of the work that you're doing. MH Well inflation statistics impact pretty much every aspect of UK society. They're used to uprate pensions, government guilts, student loans, various benefits, taxes. So, we have a very low risk appetite in terms of transforming our statistics because it is absolutely essential that we get them right because the implications are enormous if we do not. And that's been one of the challenges in bringing in these new data sources and developing new methods and systems. We've had to move carefully. We're very ambitious, but it needs to be measured ambition, because we need to ensure that while transforming our consumer price statistics we get them right, and produce robust statistics that are used across the UK economy. MF Because once reported, there's no going back - there are no revisions to inflation are there? MH No, so RPI is an un-revisable index, so we do not revise. And for CPIH and CPI, there is some scope to revise the indices, but it would have to be extreme circumstances for us to do that. And thankfully, to date, we haven't had any errors in CPIH or CPI so we haven't had to cross that bridge just yet. MF Thank you for listening to Statistically Speaking and please join us for our next episode, which is quite literally a matter of life and death. To ask a question or suggest ideas for future podcasts, please do so via our Twitter feed @ONSfocus. I'm Myles Fletcher and our producers at the ONS are Steve Milne and Julia Short. ENDS

In the third episode of Statistically Speaking we talk to Professor Sir Ian Diamond, the UK's National Statistician, and Dr Louisa Nolan, Chief Data Scientist at the ONS Data Science Campus about the past, present and future of stats. We explore how the pandemic has been transformative for the use and understanding of public data and how the data revolution and the fight against COVID are changing UK stats forever. Transcript: MILES FLETCHER Welcome to Statistically Speaking: the podcast where numbers talk and we talk to the people behind them. In this third episode, we meet professor Sir Ian Diamond, UK National Statistician and Dr Louisa Nolan, Chief Data Scientist at the ONS Data Science Campus. We explore how the pandemic has been transformative for the use and understanding of public data and how the data revolution and the fight against COVID are together changing UK stats forever. But to begin I asked Sir Ian what led him to a life of stats SIR IAN DIAMOND Okay, well, I'm going to be absolutely honest Miles: genetics. I have no idea why I was always interested in numbers and statistics but I always was. And so something in my genes said I like numbers. Something else in my genes said I like numbers but numbers which have an application and a practical application. And that led me to not only be interested in statistics, but to study statistics and then to work as a statistician in academia for some decades, but always interested in numbers and their application to policy and to improving the lives of people. And if you take that as a starting point, then it's what I've always done, and led me to at times work in partnership with different government departments. And that led me to partnerships with ONS, which has led me here. MILES FLETCHER A lot of people sort of regard statistics as numbers on a page, something that can seem quite abstract, but they exist of course to help people make important decisions. Can you think of an example in your pre-ONS career, your pre-National Statistician life, where you first used numbers and statistics to actually help solve a real-world problem? SIR IAN DIAMOND Well, yes, I mean, if I go back to the very early 1980s, at that time, the observation was made, that there had been a decline in the number of children born in the UK. That was going to be a decline of around 30% in the number of 18-year-olds, and it was suggested that therefore there would be a reduction in the demand for higher education. Working initially with Fred Smith and then subsequently on my own, I was able to project the future demand for higher education, on the basis of some assumptions that the number of women going into higher education would increase, that there would be social mobility in the country as a whole. And also, that there would be an increase in what we now call widening participation. When you bring all those things together, you get a very, very different number for the demand for higher education than from simply following the number of births. And that had an impact alongside work that other people did on influencing policy for higher education. MILES FLETCHER So a busy, very successful academic career is followed then by stint as National Statistician. You're in the job, what six months last March, just as the pandemic, as we as we came to know, was starting to break. At what point did you realise that it was going to be as big as it turned out to be and that a very special response was going to be required from the statistical system, the UK statistical system, ONS, and all the statisticians in government departments, the system that you're responsible for? SIR IAN DIAMOND I mean, I think early in 2020 Miles. We identified, very sadly, the first death from COVID at the beginning of March 2020. We now think there might have been one earlier but, you know, I think very early on we at ONS recognised that this was something that the statistical community needed to really step up for, not least working with the wider international community to define a cause of death as being due to COVID. I'd say March 2020 is when we really became aware there was going to need to be some really fast and accurate estimates of all kinds of things around the pandemic, whether it was impacting on the economy, or indeed the pandemic itself, and that led to us in April to putting together a survey which estimated both prevalence but also the level of antibodies, and subsequently now of course, issues around vaccination. MILES FLETCHER So it was a very important decision point where it was realised that the traditional, if you put it that way, the main data sources that ONS and others in government were producing were not going to be enough to measure a very, very important factor in this, that's actually how many people have got the virus at any at any one time. What point did that arise and what happened next? SIR IAN DIAMOND We had a conversation early in April. We said ONS could use our ability to be able to design nationally representative surveys and to pivot some of those designs into collecting the biomedical data that are important in order to be able to identify both prevalence and antibodies, but we will only do so in partnership with other experts. And so we very, very quickly set up partnerships with the University of Oxford, the Wellcome Trust, and the Department of Health and the Office of Life Sciences. We were able to set up a team that in one week, was able to move from a decision to go for it, to design, to ethics to the first field workers collecting some data. MILES FLETCHER And it was mounting, what was by anybody's standards, a huge field operation, as you say, in very short order to get around households up and down the United Kingdom eventually, when the survey was running at full scale. To do that very, very quickly, a huge operation… SIR IAN DIAMOND Two stages Miles: the first of which is we stood it up as a nationally representative sample, which would make estimates for England. And, you know, it takes a lot of things at pace. So getting from the field workers getting the swabs to the laboratories, getting the tests, getting them back, doing some really quite sophisticated statistical analysis to make estimates. Getting all that done requires a lot of logistics, and I think the team deserves an enormous pat on the back for so doing. And then that success led to the scaling up. So that we can make original estimates so that we can make age-specific estimates. And we were able to do that. But then that was a huge scale up in September of 2020 and I think again, the logistics of scaling that up was incredibly challenging, but successful. And at the same time working with our colleagues in Scotland, Wales and Northern Ireland, to be able to produce estimates for those administrations too was something that I'm very proud of. MILES FLETCHER And the record shows exactly what was achieved during those pressured early months of the pandemic. And of course, right at the start there were plenty of people around who doubted whether the statistical system, whether the ONS and others were really capable of doing that job. Was it satisfying to confound those critics? SIR IAN DIAMOND I didn't hear them, I just got on and did it, to be absolutely honest, Miles. I knew what we could achieve in terms of both the survey which was able to measure prevalence and antibodies, but also the social survey because you need to know how people are feeling about the restrictions. You need to know how people are feeling about the pandemic. Were they anxious or not? And then as people started to talk about, for example, face coverings. What were people's attitudes to those things and, and were people adhering to the restrictions? So, there was a social survey, that was producing weekly estimates as well. That was incredibly important, and we were producing economic statistics, as well. So I have to say it wasn't a question of was the statistical system standing up and delivering a survey to estimate prevalence of the pandemic. But it was addressing a whole set of other questions, which required not only statistical collection, but in some cases, further analysis, and data linkage and a whole range of sophisticated statistical methods to be able to provide information for the government and for the population so that they understood exactly where we were at any time. MILES FLETCHER And what do you think that all that has done for the general trust the public have in the statistics that they see from us or from the media? SIR IAN DIAMOND ONS has always been a very trusted organisation. I mean, one of the important things that we have in the UK is the independence of the ONS and I think that's incredibly important and the public in all the surveys that we have done over many years have demonstrated great trust in the statistics that we produce. And I think that the public has continued to show that trust over the pandemic. And I hope although at this stage I stress I'm hoping, that the public will feel that the ONS has delivered during the pandemic and therefore will be prepared to continue to trust the ONS in the future. MILES FLETCHER Talking about the public and involvement, coinciding with this pandemic has been census of course in England and Wales and we asked every household once again to complete the census. Again, at the beginning, some said it couldn't be done because of the pandemic and others even more said it shouldn't be done because of the cost. How has it all gone? And will it tell us what we now urgently need to know about our population? SIR IAN DIAMOND We had a really very good and very strong response. We're now in the process of doing the analysis so that we can produce really accurate results and that's going to be incredibly important. Should we do a census? Well, I think a census is a statement of great confidence from a country that is prepared to say that on one day, this is a picture of what that country is and how many people there are and their characteristics. And that is so important for all kinds of reasons. So yes, it was incredibly important I think that we did. Yes, it was incredibly important that we did it at the time of the pandemic, because we needed to know where we were at that time. Of course, we will be working very hard to update our statistics over time to really understand the post pandemic world. I'd have to say also that you know, the cost is high, no question. And we will be working very, very hard over the next 18 months or so, to produce a set of recommendations as to the future of population data collection. Do we need another census or can we do things that administrative way. In 2014 we thought about this with regards to 2021 and a really good report done by the late Chris Skinner, together with John Hollis and Mike Murphy, recommended that this census that we've just done, digital first census, should go ahead, but we should aim to make a recommendation about the future. And that's what we're planning to do. It will require support from many other parts of government. I'm confident that we will get that support. And the one thing I can say Miles is that over the next 18 months or so we'll be working flat out to be able to make a recommendation that is extremely tight and extremely evidence based. MILES FLETCHER Now this whole question of whether there should be another census, actually it chimes with a reaction that we saw coming back from the public, and we did certainly get a good response rate. We reckon 97 percent of households did take part in the census and that's as good a response as there's ever been - perhaps there was a certain advantage to holding it during lockdown even - but some people asked why they have to fill in this census because surely the government should already have all this information to hand by now. How far are we down the road to be able to gather all the information from other sources already as many countries do. SIR IAN DIAMOND Well other countries do and other countries for example, particularly those in Scandinavia require a Population Register where you have to if you leave the country, come back into the country, you have to register that you are there. And if you move you have to register. We don't do that. So we do not require you to register that, for example, you have moved house or register with the Office for National Statistics. You may register with the land registry but if you don't, if you just move, we don't require you to register that. Interestingly, there is no one source for occupation in this country other than the census. So, while you may think that data are held everywhere, Miles, they actually aren't. And so, while there are a lot of government data, there are no single sources which cover a lot of the things that a Census does and also there are one or two questions that one has in the census which are attitudinal, for example. So, you ask about well being. Well the only way you can ask people about wellbeing is to ask them, so you actually need to collect those data on a census. So there's a whole set of things that we ask on the census that very simply we don't ask elsewhere. And therefore, it's important, I think that we do get those data. MILES FLETCHER And of course data has to be fast to be effective now, or certainly faster. During the pandemic again we've seen advances in how new data sources have been used: anonymised credit card data, traffic camera data, mobile phone data, shipping data to provide these really fast readings of economic impact. Novel and brought in, in some cases, and as a specific response to the urgencies of the pandemic. But will these last now? SIR IAN DIAMOND One hundred percent. I think one of the things we've seen over the last few years has been the increase in born digital data, and we need to recognise the potential benefits of those data for our understanding of society and the economy, and indeed the environment and we need to be using them at pace in every way possible. And asking the question, do they replace things that we always have? Or are they in addition? And if they are, in addition, are they really adding value? Very easy to get involved in what you might call a data deluge. Yeah, there's loads of data out there so we'd better have it. I think you have to be very, very focused on whether any particular data add value and insight to the subject under study. If they do, then I think that it's important for us to use them and to access them. If they're just simply adding some more data then we do not need to follow them up. So data for insight, not data for data's sake. MILES FLETCHER So we've had two years driven mainly, but not wholly by the pandemic, but two years of incredible progress in our statistical system. Looking to the next decade, what comes next, what do you think we're going to see in statistics and data, how it's going to be used and what sort of issues are we going to be addressing? SIR IAN DIAMOND We will be able to process ever bigger datasets and to do so ever faster. So all the kinds of things we have been talking about, about more digital data, analysis of texts, as well as numbers and data produced at speed and at pace will be the norm. But that doesn't stop us wanting to continue to collect some pretty important data, for example, GDP or inflation data and to do so, perhaps, in a new way. In the last year we've calculated GDP using some innovative data sources, but in a way which enables those long time series that we started talking about at the beginning of this conversation Miles, to be maintained. I think it's incredibly important that we do maintain time series while at the same time produce evermore exciting and new data sources. And I return finally to the point that we will still want attitudes. If you want attitudes, we'll need to continue to do surveys. So I think it's an exciting time, one of the other areas that I think we will see, real progress is improved data visualisation and improved interoperability with people. And I think that's important when it comes back to trust, if people are able to go on and manipulate the data themselves very, very easily, then again, the transparency and the openness and the use of data will be something that will remain at the heart of what we do. MILES FLETCHER That's Sir Ian Diamond, the National statistician. Now if there was one single development that made the ONS and perhaps the whole of the UK statistical system ready to cope with the pandemic, it was arguably the ONS Data Science Campus. Established in 2017 its mission is to work at the frontier of Data Science and Artificial Intelligence, building skills and applying tools, methods and practices it says, to create new understanding and improve decision making for the public good. So what does that all mean in practice, and what has the campus achieved in its first four years? Questions I put to Dr. Louisa Nolan, its chief data scientist. Louisa to take it from the top as it were: tell us, what is the data science campus and what are you out to achieve? LOUISA NOLAN The data science campus was set up four and a half years ago, and our mission is to explore new types of data, new types of technology, new techniques in data science, to make sure that we're making the most out of the data that's available, the ever increasing types of data that are available to us. And we also build capability in data science not just in ONS but across government and the wider public sector as well. So data science is really about the analysis of that data, getting that data together. But we need to get hold of the data. We need the right tools and platforms to use that data, particularly big data. It's about testing those technologies and how we do that to build those insights as well. MILES FLETCHER And when does data that you harvest, when does it become statistics? LOUISA NOLAN That's a really interesting question. And different people probably would give different answers. Statistics, I would say is a summary. So it's a summary, it might be the average the mean, or it might be a trend, it's looking at the overall picture, whereas data might be your input. So the satellite picture or the information somebody's given on the census, and statistics really is turning it into something that we can then understand broadly, what's going on and why those things are going on. MILES FLETCHER And it's your job then, in essence, to find how best to use that, those mountainous volumes of data and transfer them into usable, useful statistics and insights. LOUISA NOLAN Absolutely, and there's the technical part of that the techniques but also understanding those new types of data, understanding their quality and their bias and how we can best use them so that we produce something that's useful for decision making and not misleading. MILES FLETCHER The data science campus has been around for just a couple of years really, but what have you achieved in the time since it's been running? LOUISA NOLAN We've achieved a lot. So on the capability side we've set up data analytics apprenticeships, the graduate data science programme, the data masterclass, which is about teaching senior leaders data literacy, we've delivered face to face training, we've trained more than 600 analysts across government to be data scientists in that time. We've built data science community activities, and then we've also delivered a vast range of projects, including things around faster indicators, counting cows from space, text analysis to help automate and understand big government consultations. So it's been a really wide range of stuff. MILES FLETCHER What have you been doing, for example, with economic statistics? LOUISA NOLAN So we've been doing some really interesting stuff with economic statistics. Back two years ago, seems like it was longer ago but I think it was only two years ago, we were asked to see if we could find faster indicators which would help to kind of test the health of the economy much earlier than our GDP and official outputs. And this isn't as a replacement for GDP, just to get some faster information a bit earlier. So we had a look at what was available. And we wanted to make sure that we had data that was high frequency and low latency, obviously, if we want to understand what's going on bit quicker. But also to make sure that it had some kind of relationship to economic concepts. In the past people have looked at things like lipstick sales, or men's pants sales or… MILES FLETCHER Counted cranes? LOUISA NOLAN Counting cranes! Counting cranes is maybe slightly better, but not all of these are very robust, and actually they're terribly subjective. And if you look at them over the long term, they don't really work. So we wanted things that really related to economic concept, even if they weren't the same as GDP. We're not trying to measure GDP. So we had a look at the various datasets that were available and the first set of faster indicators that we produced covered three different datasets, all of them really interesting in their own right. So the first one was creating a diffusion index from VAT returns. So a diffusion index just tells you the proportion of businesses whose turnover have gone up since they last reported, and obviously if that starts to drop off, that's a bit of a warning signal and you might want to go and have a bit more of a look and see what's going on or why that's happening. The other two were really different. We've used VAT data before, but the other two were really different for ONS. Firstly, road traffic data. So this comes from sensors in roads, particularly used for active traffic management, and it counts the number of vehicles passing those sensors and you can also tell how big the vehicles are, so you can separate out cars from HGVs. And we think this ought to be quite a good indicator of what's going on in the economy. Because the amount of stuff moving around the country, people travelling to and from work, quite interesting and you'd expect that to be related to economic health and the movement of people and goods. And then the last one was perhaps the most interesting dataset because it's the biggest. It's a global dataset on shipping. Every ship has a tracker. When it's in motion, if it's above a certain size, when it's in motion, it has to say where it is every second and then when it's at rest it needs to say where it is every couple of minutes. So this is an amazing dataset that tracks all the big ships. So we had a look at ships coming into UK ports, the number of visits, the type of ships coming in and how long they stayed there for. We created, I think it was about 300 different time series from these and published them very quickly. The first time that ONS had done something like this, possibly the first time in the world that this kind of faster indicators had been published by a national statistics institute on a regular basis. Really interesting data. And I think that kind of set the scene. So we've gone from those initial three datasets. Over COVID, huge appetite for faster information because things were happening so rapidly, lots of changes in the economy that were unpredicted two years ago. And so both data science campus and ONS have built on that initial faster indicator output. There's now a suite of I think more than ten different faster indicators based on things like job vacancies, footfall, traffic, camera information, all kinds of things that are feeding into that picture of what's going on very rapidly. High frequency, not much delay between the data and the reporting. MILES FLETCHER To what extent has the pandemic then hastened the pace of progress in the data science campus, and to what extent have the indicators that you produced been corroborated or vindicated by the subsequent classical data that ONS produce? LOUISA NOLAN And so as COVID hit, obviously, there was a huge desire to know what was going on how well people were complying with restrictions. Were people really moving about or have they complied and stopped moving about, and also understanding the impact of that on the economy. So the campus was well placed because of our skills and the way we're set up to rapidly pick up some new datasets and have a look at them. So we very quickly got some mobility dataset. So this is about how the bulk of the population is moving about to look at how well people were, not individuals, but how well the population was complying with restrictions. And I should say here that we're we've never been interested in tracking individuals. It's all about the bulk movements, what goes on. So we very quickly got that managed to quickly stand up someregular outputs. At one point we were reporting daily on what was happening because things were happening so quickly. And as time has gone on, I think it's fair to say that the narrative from some of those faster datasets has been broadly correct. But obviously as you get the more detailed information and more of the breakdowns, the information in, you can have a more robust, accurate measurement, not just the "well it looks like it's falling really rapidly", or "it looks like it's coming back up again" kind of interpretation. MILES FLETCHER In terms of speed, the delay between data creation and data analysis is getting ever and ever shorter. How fast can this get at what point will we be able to be able to read daily readings of the economy for example, daily readings of population shift? LOUISA NOLAN I think that it's becoming possible. I don't think you'd ever, I don't think you would have daily GDP because there's so many elements in GDP that you couldn't collect on a daily basis. The question is, particularly around the economy: How useful is having daily outputs on the economy? If you knew GDP daily, how would that help your decision making? But for population if you know what population density and how that changes over a day that might be really useful because that will tell you something about where there's high density areas, how people are travelling about how people are not travelling about , over COVID. And that would help with things like your local planning, with managing big events and so on, and help us to spend money more effectively because we know where people are and we've got a better and quicker understanding of where populations might be both in the short term over the timescale of a day and in the longer term. MILES FLETCHER You mentioned observing cows from outer space as well. I've got to ask you what that involved? LOUISA NOLAN Oh, counting cows, we love this. We have a data science hub that's embedded with the Foreign, Commonwealth and Development Office in East Kilbride. They focus on supporting the UK's mission to support developing countries around the world. And one of the projects that our team is doing, our team there is doing, is counting cows. So in South Sudan, where agriculture is a much bigger percentage of GDP, a huge part of GDP for them than it is in the UK. And cattle is really important, but it's quite difficult to go out and count all the cows is a huge country. Not great roads. They've had various different issues with weather and conflict there as well. So the question was, can we get a good picture a good census of the cattle in South Sudan using satellite data? And actually, it's quite it's quite promising. We have ever better quality of satellite data, higher resolution. You can see where the camps are and you can make some estimates around the number of cows there. Getting hold of your ground truth data to check whether your estimate from spaces right is probably the hardest part of that, but it's quite exciting. And of course, if this works, what else can we do with satellite data that's helpful and means that you don't have to send individual real people out over these vast areas to count things. MILES FLETCHER That's operating on the global scale as well, but you've also been working on ways of minutely examining documents that are submitted to government in very large numbers and bypassing human intelligence to use artificial intelligence to interrogate those documents and draw conclusions from them. LOUISA NOLAN That's right. I mean, one thing government is good at is having lots of words and documents and turning those documents from data, if you like, into information and insights is a big part of what we do. So we use natural language processing to do text analysis, and we worked with the Department for International Trade on one of their big consultations, they had more than 400,000 responses. And we were able to automate that to identify themes and topics in the responses in a faster way than you can do by hand. They also covered this in the traditional ways so we were able to compare our results with the manual approach as well. Certainly the automation is faster. And I think sometimes when you've got that much information, you can get different insights, new insights from automating. But when we look at AI and approaches like that, you really want to take the human in the loop approach. So you run the things that are automated, for the bits where it makes sense, where you can find out things, you can make things go faster. But if there's something which is difficult for the AI to come to a conclusion on, that's when you bring your human in to go, oh what does that look like? Where should that sit? How should we interpret that? And it's that combination of automation, getting humans to do the bit humans are good at that's really powerful. MILES FLETCHER So the campus is a campus in both senses really. It's a campus and that it has projects and enterprise and things getting started up, but it's also a campus in the academic sense as well. And you're training people some of whom have no background in in these sorts of disciplines at all. Tell us about what's been achieved there. LOUISA NOLAN So our capability team were set a task to train 500 data scientists by March 2021. Well, we far exceeded that we trained 680 something in that time through a range of different programmes that we run. These include the MDataGov, the master's in data science for government, which we run in partnership with four universities. The graduate programme, the apprenticeship programme, face to face learning and our accelerator mentoring programme, which is brilliant. So this is open to everybody across the public sector. Pitch a project. If your project is successful, then you get for 12 weeks, you get a data science mental for one day a week to do that project and that project will be something that's important to your home department and also help the individual to build the skills as well. There's been a massive range of projects and departments who've taken part in this. I think we've had more than 250 people through the accelerator so far. It's great. So we're always looking for more mentors as well. So if this sounds interesting, always, always looking for people to help out with the mentoring. MILES FLETCHER And in the apprentices, you're getting people coming in from the local communities in many areas around where you're based in, in South Wales, and coming in cold in many cases with no background in working in these sort of disciplines at all. LOUISA NOLAN That's right. For the apprentices it's about enthusiasm and potential rather than anything that's happened before. We've had a range of people from a huge range of different backgrounds, a huge range of different ages from straight out of school all the way to people who've had several careers beforehand who've wanted to retrain. It's a brilliant way to get diversity into data science, and I'm hugely supportive of this approach. It's great. MILES FLETCHER And how do you go about applying then for any of these opportunities? LOUISA NOLAN So we advertise them, the best place to go is to look at the data science campus websites where we advertise all of our learning and development programmes. And also we talk about our projects and the other things that we're doing so you can find out all kinds of information there. For jobs and recruitment, like the recent round of recruitment for the graduate data science programme, that will be on civil service jobs, but the first place to come as the data science campus website. MILES FLETCHER What are the challenges that immediately lie ahead for the campus then, what are you getting your teeth into now? LOUISA NOLAN So I think one of our challenges is a good challenge, which is that data and data science has never been a higher priority. I think so we have a lot of asks on us. I think in four years things have changed. So four years ago, there weren't so many data science teams across government, there are more now. So we need to think, make sure that what we're offering is still the right level as other departments mature as well. I think the desire for ever faster information is not going to go away at all. So more of that, and also thinking about how we can use data, novel data and data science to support the government's big programmes like net zero and levelling up and also continuing to support our response to COVID. And thinking about what we learn from that, how we can use what we learn from that for other aspects of health as well. MILES FLETCHER And Will everybody be a data scientist in the future rather than just a statistician? Dare I ask? LOUISA NOLAN Oh, I don't know. That's a very controversial question that. I think data science, data scientists aren't unicorns there are aspects of data science, that is a subset, or if you imagined a Venn diagram have overlaps with statistics, with operational research, with economics, a lot of economists really interested in data science and big data. But also with the digital skills as well. So overlaps with data engineering and software engineering. So my hope, my dream, I don't have a dream data science person, it's always a team who's made up of all of those different skills. And I hope that more people will have an opportunity to build at least some of those skills, even if they don't call themselves data scientists. One of the other programmes that I'm really proud for the campus to be leading which we developed in partnership with the Number 10 delivery unit is the data senior leaders data masterclass. So this is a masterclass designed for public sector, senior leaders talking about data, why it's important, how you can use it for evidence how you can use it for evaluation, not expecting people to come out coding in Python, but having a better understanding of what's possible and what the right questions to ask are. So we rolled it out to all permanent secretaries. We're hoping to roll it out across the senior civil service. Also the fast stream and some of the future leaders development programmes across government and it's also open to senior leaders from the wider public sector as well. I'm really pleased about this because I think if we can build those skills at the top level, get people understanding what the opportunities are then that helps us build that capability, increase the number of people who can do that coding, improve efficiency and help use data better to make better decisions. MILES FLETCHER That's Dr. Louisa Nolan from the ONS Data Science Campus and before that National Statistician Sir Ian Diamond. In the next episode of Statistically Speaking we turn to the economy. With the rising cost of living on everybody's minds, how does the ONS keep tabs on inflation? Is there more to national prosperity than mere GDP? And is economic forecasting really just a way of making astrology seem respectable? Join us then. You can subscribe to new episodes of this podcast on Spotify, Apple Podcasts and all the other major podcast platforms. You can also get more information by following the @ONSFocus twitter feed. The producers of statistically speaking are Joe Ball, Elliot Cassley and Julia short. I'm Miles Fletcher, goodbye.

Since 1801 the UK has undertaken the mammoth task of counting its entire population, transforming over the years to uncover a wealth of information about the people of our country. With all the data collected for Census 2021 our most comprehensive quality assurance programme ever is currently under way, drawing on the unique insight and expertise of local authorities across England and Wales to help us produce the best possible statistics for every local area. With results expected in early summer, Statistically Speaking meets the people who ran the first digital-by-default census during the pandemic to find out how it went and what the results will able tell us. Transcript: MILES FLETCHER Welcome to 'Statistically Speaking' the podcast where numbers talk and we talk to the people behind them. This month we peek behind the scenes of one of the UK's biggest mass participation events, the Census. Almost every ten years since 1801 the UK has undertaken the massive task of counting its entire population. But what began as a headcount to measure population growth has gradually transformed over the years to add a wealth of information about all of the people in our country. So now, with all the forms collected, a very large programme of quality assurance is going on and that means taking data from an array of alternative sources, information gathered by the government for other purposes, to see how far that corroborates the picture that's emerging from the census forms. And also for the first time this year we're drawing a unique insight and expertise of councils across England and Wales as to use their local knowledge to help us produce the best possible statistics for every area. Taking the further evidence gathered from those 250 organisations into account, we now aim to publish the first results in early summer 2022. However, some releases of early data have already helped to shed light on the effects of the pandemic, and more recently, the response to the Russian invasion of Ukraine. Today I'm joined by Pete Benton, one of the people chiefly responsible for running the first 'digital by default' census during the pandemic, and Sanjay Jagatia one of our vital Census Community Advisors. Pete Benton, the England and Wales census, it's the largest statistical operation certainly that any government has to undertake, and it's sometimes described as the largest regular peacetime operation that UK government does. But just give us a sense of the scale of the whole thing and what's involved in numbers. PETE BENTON Well, the simplest way to think about it is we're asking everybody, every household in the country, to do something in the same way on the same day. That's quite a challenge. You know, people compare running a census with standing up the London Olympics. That's a big job but you don't have to get everybody to take part. And in simple numbers, there are about 25 million addresses in England and Wales and we need to get a response from everybody. MILES FLETCHER The ONS, it's a relatively small organisation for a Herculean task like this. It isn't a case of everybody in the ONS downing tools for a few weeks, is it? And this time around we're measuring COVID and the economic impact and all of that. So, who are the census people, where do they come from, and how long do they stay with us? PETE BENTON Well, it really does take us 10 years to plan every census. The 2021 census - I actually started with a team in June 2011, just after we'd done the 2011 census. Now, the first question wasn't how are we going to do the next one? The first question was, do we need another one or can we get the information that is so desperately needed about the size of the population from data sets that already exist? So, we spent three years looking at questions, specifically after the 2011 census, and then in about 2014 came fairly firmly to the conclusion that we do need a census in 2021. And there were seven years-worth of efforts and some people were still around from 2011. There were even some from 2001, one or two people who'd even been part of the 1981 census so you get a little bit of corporate memory, but most people are new when each census comes along. We have a small team to start with. And then it just grows. And in particular, in the last year or two, you fill up the office with the people that are going to run the operation. MILES FLETCHER As well as the people in the office, you've got to organise this huge army of people, this 'fieldforce', who actually, as you say, go out and knock on doors. PETE BENTON You're right. When I joined back in the 2001 census, just after that, that census took about 70,000 staff. And the census before that took over 100,000. By the time we got to 2011, with advances in technology able to support people in different ways, we brought that down to 35,000 staff, and for the 2021 census it was under 20,000. So actually, we've become better and more efficient as technology enables us to change the way we do things. MILES FLETCHER Now there was less activity on the doorstep perhaps this time of course because for the first time we were trying to get everybody, if they could, to do it online. What were the challenges of that particularly? PETE BENTON Well, interestingly, it's always been a self-completion job, or at least certainly for recent decades. You get a paper questionnaire come through your door, you fill it in and you give it back or post it back. The big difference this time was that we wanted the vast majority of people to do it online. There was no online option for 2011. By the time we'd given everybody a paper questionnaire, they mostly did it on paper. 16% in 2011 did it online. But for 2021 we're at 89% of households who completed the census having done it online, and 11% having done it on paper. Now that's quite a shift in a decade and so far, I think that's the highest online percentage of any census around the world. There are a few going on at the moment. Australia's has only recently happened and we're still waiting to hear how theirs went. But that shift to doing online actually genuinely for most of the population did make it quicker and easier. And for us, in ONS, because it's all electronic, we can see immediately when every household has responded and can see those that still need some further help. MILES FLETCHER The technology on the day. It was smooth, it was efficient? PETE BENTON It was fabulous. So of course we thought long and hard about how big might the peak actually be and we scaled the system to be able to cope with our predicted online demand. And we've actually worked very, very close with our estimates. At the peak we had 60,000 submissions in a 10 minute period at near lunchtime on census day. And that's the submissions, but when you think that people are looking at our website and they're going through every question, the load on the website was quite phenomenal. During that peak period we had 30,000 requests per second for information to our website, whether it was to serve the next question on the questionnaire, or to get a bit of extra information about the census. And because we built it in the cloud that just scaled naturally and easily. We worked with the cloud providers to make sure that we understood how to make things dynamically scale according to the numbers of users, and it worked absolutely seamlessly. You can imagine there were a few people biting their nails in the days running up to it, with something quite that big, but on the day it went without a blink. MILES FLETCHER Now there's always a bit of a PR push to let everybody know that the Census is taking place. This time around we had some new events and happenings taking place. Do you want to just talk us through how we drew people's attention to it, and got it onto the media and into the news? PETE BENTON It was a mixture of things. I mean, every address got a postcard through the door two or three weeks before to say "the census is coming, watch out for it". Every address got a letter through the door a bit later to say "census is coming, here's your access code". So, every address had something that said it's coming. But sitting around that was a huge campaign. There were TV adverts, there were radio adverts. There was an awful lot of stuff just in the news because we were pushing it out there and people got behind it. But we also for the first time had 300 local staff, six months before the census, just working on local community engagement, getting the word out. We worked really closely with local authorities to use all of their local networks to promote the census to every local group so that everybody knew that it was coming, and also just how much it mattered for their community to be counted. Because if they weren't counted they wouldn't be in the numbers, and services couldn't be planned to meet their needs - services like the NHS and school places and transport - these things all depend on the number of people in a local area. That campaign was essential to get the response rates up. MILES FLETCHER And it's the campaign that has to reach the parts that other campaigns can't reach because, when you're trying to reach every single household in the country, there's always quite a proportion you cannot reach through the media. Who are those people, and how did we get them particularly? PETE BENTON So, we translated all of our materials into 50 different languages. And we had specific adverts in certain languages on the radio and on the telly, and we were tailoring the content and tailoring the networks we were using to get the broadest reach we possibly could. And we estimate that after census day, well over 95% of people were aware of the census and knew that it was coming. It was incredibly successful and it translated into over 97% occupied households actually filling in a census, because only one person for each address needs to do that. So you don't have to have every person knowing that it's coming but at least have one person from every household. MILES FLETCHER And that engagement of course comes to a head as Census Day approaches. We have buildings being lit up in the census colour of purple; we had mentions on soap operas; you're on the BBC One Show as well, banging the drum for the Census. And what was fascinating is that you could see in real time, because so many responses were coming in online, the completion rates were being boosted by those appearances as they took place. PETE BENTON Absolutely. We had real time dashboards telling us both how many people were on our website and how many were completing the questionnaire at any given point in time, and you genuinely could see spikes where the number of people on our website jumped fivefold in a particular minute when the census was mentioned on Gogglebox. And you saw peaks when the census was talked about in EastEnders and on The One Show and BBC News, and then when the TV advert went out on the Saturday night before census day, you could see it in the Ant and Dec broadcast. So through the spikes you could see the impact of the advertising that we did. MILES FLETCHER So, you could see some of these early returns going well, but what's it like to be in charge and responsible for that huge operation on the morning of census day itself? Does it feel like Christmas day or do you wake with a sense of trepidation about whether or not it's all gonna work? PETE BENTON Well, by the time you get to Census Day, interestingly, you kind of have a sense of how it's going because the letters land on every doorstep three weeks before Census day. So you've got a sense of how many people have been responding, and what times of day they've been responding, over previous days and previous weekends. And interestingly, we had the weekend profile from the two previous weekends before census weekend and we could see on the Saturday and on the Sunday what time of day the most responses came in. And it was typically about 11 or 12 o'clock. So by 11 o'clock on the Sunday of census day we knew that was the peak hour probably, from what we've seen the week before. We knew by seven or eight o'clock how big that peak was likely to be, because on previous weekend days we'd seen that eight o'clock peak was about a quarter of what the peak was going to be at lunchtime. I can't remember the exact numbers, but I was looking at seven or eight in the morning to try and predict "how high is the peak?" and what's the total likely to be. And by the time we got to 10 o'clock I think we were comfortable that the peak looked like it would be manageable within our projections and it certainly was. MILES FLETCHER And that continued then according to your expectations during the day. Did you have a sense then, come the end of that day, just how many people had completed and whether you were on course for success? PETE BENTON Yeah, we could see that we were ahead of what we'd expected at that point. And that is a census-takers dream because you can imagine knowing that you've got this fixed window as a census day. It's a fixed day, there's a period of letters that are going to come out and remind those that haven't responded after the census date, and then a fixed period of field staff. And you know you're on tenterhooks waiting to see whether the response is going to come in quick enough and be big enough. And by the end of the Census Day, we could see actually things were going well and at that point, you can breathe and say, "Okay, we're going to be alright", you know. When things go wrong it can be horrible. There are stories from around the world of websites breaking on census day and front page news for weeks as the public follow this kind of scenario unfolding, and you know that God willing, we won't end up there, but you know that it's possible and so as you get towards the census there's both nerves and excitement kicking in. MILES FLETCHER Okay, so by the end of census day you've got a pretty good picture of how well you're doing, but you know that not every household can possibly have completed it. What do you do next? How do you pull in those remaining households that haven't taken part? PETE BENTON So there's probably three big things that we do. We continue the publicity campaign, we look for the opportunities to get on the radio and on the telly and just talk about how well it's gone. We put press releases out so the conversation continues, and that was really successful. But then we can see of course, which addresses have responded and which haven't. There's a slight lag in the ones that have come back as paper questionnaires - it takes a while for those to be receipted. But nonetheless, we can see which addresses haven't responded, and at that point we send a reminder letter. The most effective thing we can do is send a letter - it would cost an awful lot more to send a person out on the street. Firstly, we try and get people to respond without needing a reminder through all that publicity campaign. Secondly, we send reminder letters and people can get three or four over a period of three or four weeks. And then after about a week, that's when in earnest we start sending out field support staff to go knock on the door and say "we see you haven't done the census yet, can we help?" And most people would say "oh, I've done it" or "I'm about to do it", and they would genuinely get on and do it. But there were some that needed a few more reminders than that. But eventually we could see that those letters were working and that the field responses were working. And of course there was also the option for people to fill it in on telephone, if they couldn't get online weren't able to fill it in on paper, but could do it more easily over the phone. And so by making multiple options available and making sure they were well promoted, we got a fabulous response. MILES FLETCHER There was an issue wasn't there with some people who thought they completed it, but hadn't pressed 'Submit', and were then getting chased up. PETE BENTON That's right, the Census is a legal document and you actually have to say "to the best of my knowledge and belief this is a true reflection of my household" and press the submit button. And there were a few people who had got to the end, thought they've done the job, but hadn't pressed 'Submit'. And so actually, they ended up getting a letter that was very specifically worded that said "we can see you've started the census online, but you haven't yet pressed 'Submit' would you like to get back and finish it off?" And we saw a good response to that as well. I'll let you into a little secret. I actually got one of those letters. It wasn't because I had forgotten to press 'submit'. It was because my kids actually weren't at home on census day. Two of them are out of the country. And I was debating with them. When are you coming home and are you to be counted in the census because there are some quite precise rules. Because if you're out of the country for more than 12 months, you shouldn't be counted, but if you're out of the country for less than 12 months you should. So we were just discussing "when are you going to be home? Do you think you'd be home within 12 months?" They said yes, but we didn't quite get there by Census day. I'd filled in my bits, my wife had done hers, as had my stepdaughter, but I was just waiting for two bits from my other kids. And it was fabulous that they could using our access code from our household which I shared securely with them via a secure link. They could go in and fill in their details, pass it back to me and eventually I pressed 'submit' a few days after census day. MILES FLETCHER How difficult was the decision to go ahead with this census, despite all the years of planning? How difficult was it to press the button and go ahead despite the fact that there was a pandemic still in full swing and the country was still in effective lockdown? PETE BENTON Well, you can imagine that was one of the biggest decisions that we've made. And in principle there were essentially two questions that we asked. The first was "can we keep the public safe? And can we keep our field staff safe?" And the second was, "can we get good statistics?" And you can gather from the fact that we went ahead that our answer to both of those questions was "yes, we can keep people safe and we can produce good statistics" but we spent a lot of time looking into that and we actually changed a fair bit of the operation. All of our recruitment and training for our field staff moved to being online where sometimes we might have gone into somebody's home to give them support, we were very clearly not going to be going into anybody's home. We kept two metres distance, we kept masks on at any point where we did do a field visit, and even doing those field visits there's a big decision to go ahead and continue. We had options just to use letters to remind people. But we went ahead and we got good statistics. We had to give some extra guidance here and there for certain questions. When we asked "Where do you normally work from, at home or in the office?" We always ask that because many people always have worked at home. But people we saw as we tested some of those things out were kind of thinking well, "what do you mean, do you mean now or do you mean prior to the pandemic?" So, we gave some guidance on a few questions to say answer now, as it is now. So that guidance was clear and straightforward. But there will be some interesting artefacts that we find from this census. So one of the questions the census asks is "Where do you live? Where do you work? And how do you travel to work by car, by train or by bike or by walking?" And of course in the middle of a pandemic, most people, or many people, weren't travelling to work. Post-pandemic we're seeing more people travelling to work, albeit they will never get back to the levels before. So the census itself will show not many people travelling actually, and the census is used for planning transport. How wide do the roads need to be? How many trains do we need? That's all based on census information. And so we're going to need to find ways to update that information after the census for some of those things. MILES FLETCHER So the operation benefited hugely as it turned out, from having what was literally a captive audience – people were at home and ready to take part, as it turned out in large numbers. But just how big a problem is it that it was done in those unusual circumstances that you mentioned? Indeed, might it even be necessary to do one again after a few years, rather than wait another 10? PETE BENTON Well, actually, when you think about it, it was critical that we did it at that time. We just left the European Union and we were at the heart of the pandemic, and it gives us a fabulous baseline. We know that the population will continue to change as we adjust to a new normal, whatever that might be - no one knows what that's going to look like. So having that baseline to say where were we, and then every year to refresh those statistics and say: How has the population changed? How has the way we work changed? How has the kinds of jobs that we're now doing changed? And how do we travel to work - how has that changed? So what we're now planning is frequent updates to our statistics, both how many people are in a local area and what types of people are in a local area, using all kinds of new information sources to chart out the change post pandemic and post Brexit baseline. MILES FLETCHER So it's a successful operation. People were convinced about the need to take part. They took part in very large numbers online. Just how successful do you think it was then? PETE BENTON We estimate that we got a response from over 97% occupied households. Now that is quite something. We set ourselves a target of covering 94% of the whole population in the census responses, but that is just the first step. You know, knowing how many addresses have responded is the beginning. But different addresses have different sizes. Some have more people in than others. And it might be that some of the addresses that didn't respond, the few, were either larger or smaller than the average address. So we don't know yet what percentage of people we covered and there are some fairly clever processes that we go through to actually work out who we've missed. MILES FLETCHER In historic terms, how successful is a 97% household completion rate? PETE BENTON Well, in 2011 we estimate that we hit 94%, and something similar in 2001. So 97% is pretty good. But actually we've got a bit more information this time about those vacant addresses than we would have had in the past. In the past, all the record books that the collectors used were on paper. For the first time in 2021 all the field staff had a mobile phone with an app on it that gave them their workload and they could record the outcome of every address that they visited. And so, within a moment, we knew centrally every address that the field had said "this one is vacant". We've never had during the operation that kind of information before, we've always waited till the end and we've always talked about what percentage of the population we've covered. So in a sense there isn't a comparable figure, the comparable figure will be 'what percentage of people did we count'. But nonetheless we're pretty sure that 97% is good going. Of course, in 1801 we have no idea how many addresses were covered. We've got the results, we know something about how they did it, but they didn't have computers, they didn't have address lists. They didn't have extensive records. A lot of it was managed by people just keeping track locally of what was going on. So we're getting to a world where information becomes more and more finely detailed as we go through running these operations MILES FLETCHER And to get a better handle on what you don't know as well as what you do know. PETE BENTON Absolutely. And in the last three censuses, we've actually made quite a big step in how we assess that total coverage of the population. To plan public services you need to know about everybody, every different community group, every age group in every part of the country. As you can imagine, doing a census, there are some groups that are more willing to respond than others. Older people tend to be more diligent in completing forms, certainly more diligent than students and young men or busy young families. So we know that sometimes we miss people because they're busy, and they just don't quite get the census done, and we make adjustments for that. But what we don't want to do is just add a percentage of all age groups. We want to assess who have we got a high response rate from, and who have we got a lower response rate from, and what adjustments do we need to make to our statistics so that the results do the very best at representing the whole population, even if we didn't count every single one of them. And there's a technique we use called 'capture / recapture', and it's used for wildlife if you want to count how many ladybirds there are on an island or how many fish there are in a pond or even how many taxis there are driving the streets of London. There's a technique you can use, and then we apply it to the census. So let me talk you through that step by step. And if you're really interested in this, there's a little article online. It's called Trapped Catfish and Roach, the beginner's guide to census population estimates. If you Google that it's only a few pages long and all you need to read is the first page but I'll explain it to you now. So, you get the idea. Just supposing you've got a pond in your garden and you'd like to know how many fish are in it, and you could drain it obviously, but that's a lot of work and it wouldn't do the fish much good. So instead you catch as many as you can, and supposing on the first day you catch 100 fish, then you very carefully put a little tag on them. Then you put them back in your pond. You let them all mix up and you go back the next day and you go fishing again, and this time you catch 50. And you find that 25 already have one of your tags on them. How many fish out there in your pond? MILES FLETCHER I don't know. I'll blunder a guess and say 400. PETE BENTON So what you do know: you saw 100 Fish on day one. And on day two, you saw another 25 that didn't have a tag, so at least 125 are in the pond. You can be sure of that. But you can guess there's going to be more swimming around that you've never seen. But the interesting thing that you learn on day two is that half the fish in the pond probably have a tag because you caught 50, 25 had a tag - half of them. So you can kind of have a guess that maybe on day one you tagged half the fish. Given that you tagged 100 that means there are probably around about 200 in the pond in total. And you'd be right, give or take a few. And the question is give or take how many? And the interesting thing is the more you catch on day one and the more you catch on day two, the more confident you can be. So we catch as many as we can in the census - that 97% that I told you about is our first day and we don't put a red tag on people because everybody's got a name and an address, and a date of birth, and the sex, and we know that from the census returns. So then we go out again about six weeks after the census and rather than ask people to fill the form in we say will you just do a quick interview with me? And we asked them their subset of the census questions again. Then we do it just in 1% of postcodes, and we list all the addresses blind we don't give them an address list this time. We say here's a boundary on a map. Here's a postcode. Go and list the addresses and go and interview as many people as you can. And they've got names and addresses, and sex, and date of birth. And we literally match the two together, and we go to about 300,000 addresses when we do that. And in doing that we can do those sums. How many do we catch first time? How many do we catch second time? And we can estimate the total but because we know everybody's age and sex we can see how it varies for different age groups. And we also ask ethnicity and we see how it varies for different ethnic groups. And we also can see different housing types. So big houses, small houses, and we break it all up into those subgroups, do the estimating and then add it all up. And that tells us in total what percentage of people we've missed in those 1% of postcodes, where we did that second count. And then we take that information and we kind of generalise to the other 99% of postcodes where we didn't do the second count and with a whole bunch of fancy maths, we can estimate the total population. MILES FLETCHER And that is how you fill in the missing 3% of households. PETE BENTON Exactly. And we pride ourselves on not just doing that nationally, but getting it so that right down at the small areas of the country. All the totals add up to the total number of people living there as best we can estimate it. So, a lot of work. It takes us a while. And interestingly, we're the only country in the world that attempts to do that process before publishing the census results. Other countries will typically publish the raw count, accepting they've missed a few, and then they'll spend the next year or so looking through the data and adjusting their overall totals but they don't adjust the small area data in the same way that we do. MILES FLETCHER So we're at the point now where all the data has been gathered. ONS has gone away to go analyse it all and we have the wait for the final published statistics, including of course the most important population estimates of how many people are in the country and where they live. PETE BENTON So, the first job is not just to collect the stuff that came back online, but also to scan every response that did come back on paper. Whilst it was only about 11% of addresses, that still amounts to somewhere near 3 million paper questionnaires. Each one of those is 30 pages long - it takes a while to scan all of that and to catch the data and we do it with computers using optical text recognition. They're all in there, very secure, confidential processing operation. So it took us till about August to get all of that data captured. Then we put it in the mix and we merge the whole lot together. And you know, the interesting thing is you find some houses that have responded twice. So they've sent you a paper return and somebody else has sent you an online return. And even sometimes, people are counted in more than one location different people in different addresses. Parents count kids. Like mine. Parents of divorced families may well both count their kids, so we do a check next of any duplicates and we remove the duplicates. And then sometimes people do give us some unusual answers, like, you know, children who are three years old and they're married or working in a factory and we do our very best to try and tidy up some of that so that at least what we're publishing is consistent and, you know, we'll kind of say for three you're probably not married and fix some of that. Sometimes people do skip a question and we'll do our best to estimate. Based on their near neighbours, what might the answer have been if they didn't fill in the question about what kind of heating they have in their house? If 99% of the houses around them have got gas central heating, we'll take a punt and say it is probably gas. So you get better statistics that way. So, there's a bunch of tidying up to do. And then there's the work to estimate how many people we've missed by linking it up with our Census coverage survey data. That in itself takes another while and then our estimates come out. And then the next job is to say okay, do those estimates make sense? And we compare it with other sources for how many people have got a National Insurance number, how many people are registered with a doctor, and do our results sit comfortably with those other sources. So, a lot of work to make sure the results are plausible and make sense to when they come out. They're as valuable as they can possibly be. MILES FLETCHER So this huge sense checking operation takes part so that the statistics as you say are as valuable as can possibly be. What can we expect to see first then, is everything going to be released? PETE BENTON So the first thing that we will do is publish that size of the population. By age group and sex for every local authority in the country, so that every local authority can see how many people are here and they can plan on the school places they need, and how many houses might need to be built. And then every couple of weeks after that, we will keep releasing more and more detail like how many people have got a job, what kinds of jobs people do, how's that vary by ethnic group. And then we will publish something like 5 billion numbers, 5 billion statistics, and that takes us a while to get it all quality assured, to get it all published. But for the first time we will also make available a flexible table builder so people can take a look and say, well, could you give me a count of how many people are this age and working in this kind of profession, who are of this ethnic group, who are gay or whose gender is different from what was assigned at birth, and people can actually produce their own statistics. Now we double check to make sure there's nothing that's being published that has any risk of identifying a person, because you've got small numbers. But that flexible table builder will mean people can answer some of the questions that might have taken longer in the past more quickly. MILES FLETCHER Billions of data points. How do you make it so detailed to be so very useful, and yet protect anonymity? PETE BENTON Well, we spent a long time making sure the questions work in the first place so that when people see this question, they're not answering what they think we're asking. They're answering what we're actually asking. But then on top of that, there's a lot we do to make sure that when you see a table that has got small numbers in it, and you might think "oh, that's Joe that lives up the street, oh I've just found out that he works in the clinical profession" say, well, we just don't publish those statistics for one thing. We don't publish data that is that detailed on all topics so that you know people could find that out. But there's also some sophisticated methods that we call 'statistical disclosure control' – world leading methods, actually. That means that when you look at a given table, you can't be confident that a number that you see actually is absolutely correct. In the totals, the numbers are right. But if there are some fairly unique people with unusual characteristics that would stand out in a table, interestingly, we'll often swap them with a household somewhere else. We will take one record and literally move it somewhere else, and swap somebody else back so that you don't know for sure who's there. And then even when we publish the numbers at the end, sometimes we'll change a number too. If there's a count of two people we'll change it and make it a bit bigger or a bit smaller and we can do that to any particular number in any table. And we've got some really world leading methods to help us do that. So when you look at the numbers, they're accurate, they give you a good picture in total of what's going on nationally and in a local area, but you can't identify any individual with any kind of confidence. MILES FLETCHER So there is a very great deal more to anonymity than simply withholding people's names and addresses. PETE BENTON Absolutely. And in a world with more and more data, these methods get more and more important. MILES FLETCHER The big question, of course, is whether that was the last census of its kind that we're going to see in England and Wales. PETE BENTON Well, I wish I could answer that question today. It's certainly our intention. We are working as hard as we can to find new ways of counting the population, using data that exists in government. How many people are getting benefits? How many people are paying taxes? And can we join that information together to get a good clear, detailed picture of local communities. And we're making really good progress, but we're not going to make a decision until we've been able to compare the results of our alternative new methods with the results from the 2021 census. So, we'll do that and come 2023 we'll make a recommendation - do we have another census or don't we? MILES FLETCHER Pete Benton – thanks very much. SANJAY JAGATIA My name is Sanjay Jagatia. I'm actually based in Coventry. As part of my voluntary work, I'm also the chair of the Hindu Think Tank UK, which is an umbrella organisation for the Hindu community across the country - almost 1.5 million Hindus across the country from the last census. And then also the Vice Chair of the organisation of people of Asian origin in Britain. And it was through that that I felt that you know, I wanted to have the Indian community being represented as part of census 2021. And when I saw the advert come through, I thought this was an excellent opportunity for me to personally do whatever I can to encourage as many from the Indian community to take part in census 2021. MILES FLETCHER You've told us already that you thought that working for the census was a life changing experience for you. Tell us about how it has changed things for you? SANJAY JAGATIA I think for me it was life changing because I was one of the sceptics initially about how census data is used and what benefit, more than anything else, what benefit does it have on me as an individual and as me representing my community? What benefit has it had before? I hadn't noticed and I hadn't realised the enormity of the whole process and how important it is, not just for us as communities, but how local authorities and how everybody else will use that data. So, we had to be counted. And that for me was life changing. It was also life changing to see people from the age of 18 to 99 in some cases, wanting to be part of this. And the enthusiasm that has built for the first three, four months coming up to census - that for me was really, really important because I haven't seen that engagement ever before in my community for any issue that's happened. Even when you look at voting days, election days and all the other things that happen, that enthusiasm was not there as much as it was on this occasion to be part of census. MILES FLETCHER And what does an engagement manager do to make sure that happens, that people do get themselves covered in the census? How do you go about that work? SANJAY JAGATIA When we first started, I did research in the area of all the various Indian community organisations, key individuals, people who had a large social media following as well, and started to engage with them initially because without them, I knew that my work would have been very, very hard to be able to reach their communities and their membership that they had. So that piece of work that we did right at the beginning of the census, which was a three week period of researching the entire area to find out where people were, and who the key individuals were, that we can actually engage with the census. And what I did went a little bit further and I identified individuals who we made census champions - people who were able to work with me right throughout the period of the six months of the census. MILES FLETCHER How did you persuade them that championing census was a worthwhile thing for them to do? SANJAY JAGATIA I think you know that the previous census 2011 and in Kenya prior to that, it was clearly evident that we saw that the Indian community's engagement was very, very little compared to other groups and minority groups as well. So, this was a key area for me to be able to say you had your opportunity or we have our opportunity of having our voice heard, you know, whether it was roads, transport, education, and what may be available for our communities in our local authority areas. And I think having examples of how other communities have actually used the ONS Census data previously for their faiths and their communities was a really good way for me to be able to engage with my own community to encourage them to take part in the census. MILES FLETCHER What do you think it was that was preventing your audience from previously taking part? Was it just a lack of awareness? SANJAY JAGATIA I think the awareness this time round for Census 2021, in my opinion from my community, there was a lot more awareness a lot earlier. And I think that was because of the focus group meetings that were held with key individuals from each community in each faith. And I think back then it started to filter down to communities at least six, seven months in advance of Census happening. And I think from my point of view, I think it was a lack of awareness of census and how important census can be for each individual and I think that's why there was a low uptake on Census previously. But on top of that, as well, I think that there is an area where we have cultural differences, language differences as well. And I think that that was key, that a lot of information previously was very much in a mainstream English language, which was sometimes very difficult for those within the community who are elderly to actually understand that. MILES FLETCHER And did you just target areas where there were known to be lots of people with Indian heritage? Or did you seek to look at some areas, or identify some areas, that were perhaps less well known? SANJAY JAGATIA Yeah, I mean, to be honest with you, from my personal point of view, I wanted to have a look at those areas where there was a low uptake before, to try and see how I can actually engage them a lot earlier than those who I knew that there was larger, you know, quorums of people from the community. So my initial stages were actually looking at those areas where there was a low uptake previously. MILES FLETCHER So you're signed up, you've got census champions, you've got a mission to go out and identify those areas where we could engage Indians, people of Indian heritage, a specific community with the census. Tell us how it went out there on the road, on the doorstep, on the airwaves. How did it go? SANJAY JAGATIA Yeah, I mean, to be honest with you, right from the beginning, in October, November time, when I was recruited for the role, it was very daunting. You know, because we were in a major pandemic. We were in lockdown at the time and I was thinking to myself, as well as my other colleagues from other areas that how on earth are we going to engage with people because it's going to be virtual. So, it was daunting to begin with. But you know, when I look at it now , we had so much support from the ONS where we were able to have all of our questions answered, the regular meetings that we had, the updates that we had as well, which then allowed me to start to work with the key champions, also the key individuals that were going to be working with myself and started to put together items and articles that they could use on social media, through their E newsletters, and trying to capitalise on what they were doing already, because they were also in a COVID period and they were engaging with their communities on a regular basis. So, I then asked to be part of any communication that they were making to their communities and regularly feeding them information about the census that is coming. It's 10 days away, it is here now. You know, these are the information that you can actually go on and do online. I was very, very fortunate that throughout my period of the engagement, I conducted over 188 Zoom calls and these calls ranged from anything from 10 people on the Zoom call to some cases, over 800, 900 individuals. Along with that there was you know, where we got temples involved. So I had a zoom call with just temple heads, you know, the President and the Secretary. So that was something that I was able to do and it really, really proved worthwhile for me. MILES FLETCHER So, because of lockdown and the pandemic, and all the uncertainty of that, you had to go electronic and run down the streets to get the right people in front of their laptops. SANJAY JAGATIA Absolutely. And I think if I look back at it today, I really don't think - and I honestly believe this - I don't think that I would have had the success that I had in Coventry had it been just face to face engagement. What was daunting to start off with actually proved to be so beneficial to be able to have that opportunity of reaching more people at the same time. You know, I was thinking of holding meetings in community centres and in places of worship and you know that you'd get 10 / 12 people coming to those any one time. It's difficult to drag people out of their homes to come for a meeting to talk to them about something like Census, but the fact that they were able to actually engage with myself, and me to engage with them in the comfort of their own homes was a fantastic opportunity. MILES FLETCHER What sort of reservations did you encounter that people might have had about taking part in this Census? Perhaps of dealing with officialdom and handing over information to officialdom, perhaps? How did you how did you overcome those? SANJAY JAGATIA I think that the biggest barriers that I had right from the beginning was that even though the ONS wasn't a governmental department as such, people felt that the information that they were going to be giving may have an impact on their benefits and their rent and all sorts of different issues that they may have personally, you know, whether they were illegally living in the UK, for example, and I think that was a reservation to start off with. The amount of information that was being asked initially, there was this fear about letting that information go out into the public domain. Having said that, once we started to get the dummy or the draft questionnaires that we were going to get people to fill in. I think the whole spectrum changed because it wasn't as in-depth information that they were thinking initially that they had to provide. MILES FLETCHER And of course it's an important message at every census time that all of the information you share, all the personal information that you share, of course, remains absolutely confidential for a very long time indeed. Do you think the people you were dealing with were perhaps more receptive to hearing that message from you perhaps as someone with status in the in the Indian community? SANJAY JAGATIA Yeah, I mean, I think one of the key things there is that it wasn't just myself but the idea of engaging community leaders who they have a very good link with. That was a key thing for me that they listened to the community leaders and the key influencers and then their reservations were sort of somewhat limited thereafter. MILES FLETCHER Overall then share with us if you would some of the most rewarding bits of this experience. What would you chalk up as your biggest successes and most rewarding experiences? SANJAY JAGATIA I think the biggest thing for me was actually census day, you know where I had zoom meetings right from 7:30 in the morning, right the way till 11 o'clock at night, and the urgency in people wanting to make sure that they take part in the census on that one particular day. Even though they had the opportunity a week before to start this, it was census day itself and the urgency of "yes, I want to have my vote. I want to have my say. I want to be able to say what I want to do going forward in the census". I think that for me, that particular day was fantastic. Not just online but to be able to go out and help people fill out their census form as well going out into the city centre, going out into some of the areas where lockdown restrictions slightly had been lifted at that time. And that was a really, really a brilliant occasion for me. MILES FLETCHER I'm sure Sanjay a lot of the credit for that then rests with you. The proof of the pudding will come where we see the results of course, but in the meantime, thank you very much for joining us today and thank you very much for everything you did for 2021 census. Thanks to Pete Benton and Sanjay Jagatia. In the next episode of 'statistically speaking', we're joined by the National Statistician and the chief data scientist at the ONS data science campus. We hear from them how a data revolution and the fight against COVID changed UK stats forever, how we kept the numbers coming at a time of crisis, and how ONS statisticians are using faster forms of data to gain ever clearer new insights. You can subscribe to new episodes of this podcast on Spotify, Apple podcasts and all the other major podcast platforms. You can also get more information by following the @ONSfocus Twitter feed. The producers of 'Statistically Speaking' are Elliot Cassley and Julia Short. I'm Miles Fletcher. Goodbye ENDS.

Since April 2020, the Coronavirus (COVID-19) Infection Survey has provided vital weekly snapshots of the level of SARS-CoV-2 virus circulating within the community. We're joined by three central figures in the project, Ruth Studley, Tina Thomas and Professor Sarah Walker, for the inside story on one of ONS's most ambitious surveys, set up in a matter of weeks as the pandemic took hold. (This episode was recorded in September 2021, before the emergence of the Omicron variant) Transcript: Miles Fletcher, Head of Media and Public Relations at the ONS Numbers, numbers everywhere, but here we'll take some time to think about where they come from what they mean, and where they're going. Welcome then to the first episode of statistically speaking the new official podcast from the UK's Office for National Statistics. In this series the nation's number crunchers, as some people still insist on calling them, chew the fat and spill the beans on the stories behind the stats. Lately, they've been making headlines, some would say ruling our lives, like never before. I'm Miles Fletcher and in this first episode we'll be looking at how millions of swab tests and finger prick blood tests allowed the Office for National Statistics and its partners to track the progress of COVID-19 across the UK. During the pandemic, the COVID infection survey has proved a vital source of regular data on Coronavirus infections, antibodies and symptoms. We'll hear why this huge study was needed in the first place, how it was set up in double quick time and what it's told us about the virus and its human impacts, and why it remains important now. Joining us are three central figures in the project: Tina Thomas, who runs the survey operation itself, leading a force of thousands of study workers out gathering data in the field; Ruth Studley Head of Analysis for the ONS, whose job it is to turn those test results into fast statistical estimates that we hear about in the news every week; and from the University of Oxford, the chief investigator and academic lead of the infection survey, Professor Sarah Walker. Sarah, to start with you first, how did this study get underway? And well, why was it needed in the first place? Professor Sarah Walker, Chief Investigator and Academic Lead for the COVID-19 Infection Survey So it was back in April 2020, when a lot of people had, you know, been sick with COVID in the first wave. But we really didn't know how many because at that point, we didn't have the PCR tests that are done in the laboratories, we didn't have the tests on a stick, the lateral flow test that lots of people do before going to school or work. And we really have no idea how many people had actually already had COVID. And at the time, there was actually a hope that we might even be close to herd immunity then. And so initially, in the middle of April, the infection survey was first of all a study looking for antibodies in the blood. And the initial plan was to sample just around a thousand households in the first month, then a further thousand households a month for a year to just find out how many people had had COVID already. But over literally the course of two or three days from the 17th to the 19th of April, we realized that actually, we didn't know so much more, in particular about how many people were infected without having any symptoms, how many people were passing it on to other people in their household, how many children were infected. And very rapidly, the survey increased to sampling over 11,000 households in the first month with an initial plan to then resample another 11,000 households a month for a year. Miles Fletcher Quite simply, you needed to have that representative sample of the whole population, it wasn't enough just to rely on people coming forward who suspected they had COVID. Sarah Walker Well, exactly, because what we cared about was what was really going on in the community. And it's well known that people who come forward for testing tend not to represent their communities completely. And so this was why initially, just because we had to get going so fast, we did actually approach at random people who had been in previous ONS surveys and said they would be interested in taking part in future research. But very quickly, we moved to just sampling from addresses. So, to really get a completely random sample of people living in private households across the UK. Miles Fletcher And how did that connection with the ONS come about? Because it's a new departure for the ONS, we normally measure the economy and migration and so forth, but not medical testing. So how did that partnership get started? Sarah Walker So, I really think it was a case of everybody just working as hard as they could together to make this happen fast. And what ONS do have huge experience with is these very large population representative sampling frames, and they also had access to this databank of people who had been randomly selected for previous surveys and who had said they would be interested in taking part. It's a huge field operation and obviously ONS has got huge expertise in that. So, I think they were in many ways, you know, the obvious partner to really take it on. And it was a huge collaborative effort between the Department for Health and Social Care as well as the University of Oxford and ONS. Miles Fletcher And this all had to happen in a fraction of the time that's normally available to plan a big survey, for example a census, and it was almost on that sort of scale. You need every community, every age group or socio demographic group represented in that massive sample. All this had to happen in a matter of a few days to start with to get the first estimates. Sarah Walker We wrote the first draft of the protocol on Friday the 17th of April, we submitted it for ethical approval on Monday the 20th of April. So that's just four days later, during which time we had gone through three major changes in scope and size. It was approved on Tuesday the 21st of April, we recruited our first participant on Sunday, the 26th. So literally ten days after the first draft, and we published our first estimates two weeks later, on Sunday the 10th of May. And interestingly, the positivity rate was 0.24%, around 136,000 individuals in England which we thought was enormous. Miles Fletcher Oh, well we'll have a lot to say about what we've actually found. But just thinking about those early days and having to achieve in a matter of just a few days, what would normally take months. Tina Thomas, what was your reaction? What was your reaction when you first heard about this project and what it was trying to achieve? Tina Thomas, Deputy Director for the COVID-19 Infection Survey My reaction! So, before COVID, I was running the ONS social survey field community, and that's about 1,200 people, 1,200 interviewers, so they were keeping me busy. I had a phone call from one of our deputy directors on a Sunday night. They said, they want us to run an infection survey and they need me for the operations. And to be honest with you Miles, last year was a little bit of a blur. Usually, when we do surveys like that we take our time in working out the actual survey model, how are we going to do it, what we need, what our end goal is. And like Sarah has just articulated, everything was needed within days and weeks. To submitting a protocol on a Friday to recruiting our participants and the field staff out in the field, collecting the swabs and asking the questions was just short of 10 days, I believe, which was just something that we had never, ever done before. Did we think we could do it? There was a lot of nervousness but there was also so much passion to get this out there because we knew how important this data was. And everybody who worked on this, as Sarah said before, a huge collaborative effort to get it started. But it was just something that none of us had ever tried to tackle before. And it just proves what you can do. At pace, under pressure – we did it. Miles Fletcher And it's a huge collaborative effort involving not just Sarah and her academic colleagues at Oxford, but also the University of Manchester, a whole fleet of specialist contractors helping us to run the field study and specialist providers of all sorts right across the country. And, of course, government partners, chiefly the Department of Health and Social Care in England and the devolved administrations in Scotland, Wales and Northern Ireland. This is a huge UK-wide effort. Now in those early days, of course, it's the start of the survey, it started in a relatively small scale. It was, as I recall, about 12,000 households to start with, but then it grew rapidly didn't it? Tina Thomas Yes, that's right. I think it was, it was changing hourly some days. But yes, it started off relatively small and then it was within a matter of days "we want 150,000 unique participants providing swab samples across the UK". We started off in England, we didn't actually bring any of the devolved nations onboard until around about the summertime, so a couple of months after the study had been running. That involved Scotland, Northern Ireland and Wales, which really brought its own operational challenges. Scotland and Wales are obviously a bit more rural than England. They wanted us in Scotland to go to the highlands and the islands and of course, going into Wales everything had to be translated into Welsh. And we had to make sure that we had Welsh speakers who could answer the phones for queries and also study workers that could speak Welsh as well. So really what was going on in the background from an operational perspective was very, very much like the swan analogy. We seemed quite calm on the surface, but with so much going on underneath - it was just incredible. And it's not just about recruiting those participants and getting the study workers out there. There's all the logistics around it, like how do we get the swabs to the labs? How do we get the test results back? Who's going to do all our printing? Who's going to send all the letters out? I'd wake up in the morning and think okay, so what challenge are we going to have to deal with today and I was never disappointed. Miles Fletcher And meanwhile always this huge expectation, from government, from the media, from ordinary citizens wanting to know exactly where the infections were, where the path of the virus was going. And during those very hectic early days, just one operational upset could throw the whole schedule into disarray. Fifteen months on, the survey is settled into a regular, pretty steady pattern now of hundreds of thousands of enrolled participants. And from their number, a large group taking a regular finger prick blood or swab test. How is that? Has it become easy to run now or are there still huge challenges out there? How are people, how about the participants themselves? How have they responded? And what's been their role in keeping this study running and keeping its findings meaningful? Tina Thomas So yeah, I mean, at this moment in time, we've got just over 457,000 live participants in CIS, 5.5 million swab tests have been taken to date. And just under a million blood tests. A daily rate for swab test is around 14,000, there's about four and about 5,000 blood tests being taken as well. We couldn't do this without our participants. Last year, when we had lockdowns, we had a bit of a captive audience. So, the study workers could get through their appointments. As we've seen lockdown restrictions lifted, it started to make operations a little bit more difficult. So, we've had to kind of pivot and change the way our study workers operate. So that's maybe working more in the evenings, offering weekend appointments. But our participants are just absolutely critical to this. And we can't thank them enough. It takes a lot of their time. We're asking a lot of them, but they majority of our participants are just really willing to do this. And you know, actually quite enjoying being in surveys while really feeling like they're making a difference. Miles Fletcher Tina, talk us through - we've got this small army of people out there in the field, covering households up and down the UK, tell us how the process works. Tina Thomas It's not such a small army, there's just over 3,000 study workers that are contracted to work on CIS, as you said, spread all across the UK. They are given what we call an allocation each day. So that's about visiting households to keep within protocol. So, some are still on weekly visits, some households are on monthly visits, they have to think ahead and have all their kit together: barcodes, test tubes, the swabs, the blood kits, and their mobile devices. So, they ring a household, usually the night before and agree a date and a time for them to visit. When they arrive at the household it's a non-contact visit and they hand over the kits to the household members and scan the barcodes to make sure that we get the right test against the right person when they go to the labs. That's for swabs only. If the household is blood too then it's on to the fingerprick blood tests, which the participants usually take inside to do. And then they come back to the doorstep and there is a questionnaire that they'll need to answer, which Ruth touched on, which is about if they've had COVID, if they've had symptoms, what their social interaction has been like, and obviously that's more and more important now that lockdown restrictions are being lifted. Then the study worker completes the visit. And at some point during that evening they will drop the swabs off at a courier point where they'll go overnight to the labs. And the test results are usually back within two to three days. We've recently just introduced a new process, which saves quite a bit of money and also a lot of trees in that the test results now go out to our participants by email rather than by letter. If it's unfortunate to be positive, it gets notified to test and trace who then get in contact with the household. Miles Fletcher And of course, running something on this scale, it doesn't mean things always run entirely smoothly. We've had some quite colourful encounters on the doorsteps… Tina Thomas We have! So we have had a couple of study workers who've arrived at a pre-agreed date and time for the door to be opened by somebody who wasn't wearing any clothes. That's happened a couple of times and I think actually one study worker did ask the gentleman to go and put some clothes on and he came back with a T-shirt on, which just about covered his top half. And with the finger prick blood test as well, so it's quite a neat kit that comes in a cardboard box and it's got a plaster and a lancet and the test tube that we need them to collect the blood. The lancets are not needles, they're tiny, tiny blades because the actual volume of blood that we need to test is quite high. But we have had a couple of participants who I think were laborers on building sites, whose hands were very calloused from the job that they do, where the lancet just would not pierce the skin. And because they were so willing to provide that blood sample and wanted to provide that blood sample, I think we've had a couple of instances where they've come back with Stanley knives and actually managed to get blood out the finger with that. We wouldn't approve that or suggest that's the best way to do it. But what it does show, certainly the last one, is that people are just so keen and passionate to be included in this survey that they'll do what they can to help us. Miles Fletcher Made of sterner stuff than me, willing to take a stanley knife to yourself in the cause of science. And please, everybody don't try that yourselves. Some people haven't been quite so robust on the doorstep though. Tina Thomas No. Since we introduced the fingerprint blood test for antibodies, we have had a number of participants who have fainted whilst trying to get a blood sample for us. And unfortunately, a very high percentage of those are men. But we do have procedures in place with a study worker to help people when that happens. And obviously it remains a non-contact visit. But they have got a list of instructions if somebody does, unfortunately, pass out. And I think at this point as well, Miles, I'd really like to just say a massive, massive thank you to our study workers working on this who have been out doing this, during those early dark days of the pandemic, through every type of weather you can think of, to get us these samples and the data that we need. Miles Fletcher Thank you, Tina. So Ruth, this is where you come in – the field force have gone out, they've done their job, they've gathered in these thousands and thousands of samples, what do you do first? Ruth Studley, Head of Analysis for the COVID-19 Infection Survey So, what happens first is all of those swabs are sent to the different Lighthouse Laboratories to be tested using different PCR arrangements. That is part of the national testing programme and we use exactly the same process as the rest of the UK, that then gives us a set of data which we could use. And that is sent to us securely in ONS, where we process that data to understand exactly what is going on in the raw data before we use our modelling arrangements to produce our headline estimate. So, as part of looking at that data, we want to know things like what the different cycle threshold value is, for example. Now that is a bit of a technical term, and if I try and describe it very basically, it's the number of times, the number of cycles that each PCR test has to go through before a positive result is detectable, for example. And if there's a high quantity of the virus, you would expect that to be identified after a low number of cycles. So we would say that that was a low CT test, and it will be regarded as a high viral load. And so we look at things like that. And there's lots and lots of different things that we would look at in the raw data before then moving on to doing our modelling. The modelling that we use is a Bayesian multilevel regression post stratification model. And that's used to calculate breakdowns of positivity by region, and age across England. That all happens at breakneck speed. So the data arrives on day one, and we are virtually ready to produce information by day three, we publish by day five. It's very, very rapid. I'm not sure if any other official statistics are produced that rapidly. Miles Fletcher But such as the need for that data. Have the findings ever surprised you? Ruth Studley Yes and no. So, you wouldn't expect it to change very rapidly in the course of a few days. And usually, if there is something that you were surprised by, it would usually be an indicator that you want to do some further analysis. And there have been occasions where we've seen things and thought, does that make sense? And you dig a bit deeper, and you find that there's something going on in the data. But whilst, like Sarah was saying, you would never propose to predict what is going to happen, you would expect the changes to be relatively smooth. Miles Fletcher So, out on the doorstep every day, 12,000 swab and blood tests being taken, on average, at the moment nearly 6 million in all gathered under this survey. But what happens to those test results when they come in? Ruth, it's your job to make sense of them, and to turn them into statistics that can be relied upon. What's the secret to keeping those estimates reliable and trusted? Ruth Studley So that's a really great question Miles. I was thinking when I was listening to Sarah and to Tina then, what is it about this team that has allowed us to produce such fantastic results that have been so vitally important to the UK? And I think it's the three Ps you know, we've got people who are passionate, people who work at pace, and we work in partnership. And it's all about wanting to do the right thing for the country, actually. So, what do we do with all of that data? We have a plethora of information as you have all described. And we do collect information from every participant every time we visit them on their socio demographic characteristics: whether they are experiencing symptoms, whether they are self- isolating, what their occupations are, whether they're working at home, questions about long COVID and whether they've been vaccinated, social distancing, physical distancing, etc. We ask all sorts of different questions, because it's really important that we're able to provide as much information as we can, not only about the direction of the pandemic, but also what people's experiences are in the community. And it's probably worth just reflecting there about who it is that we are sampling and who we're representing. This is a survey of the community of the population at large. So we will be testing people who are both symptomatic, but also are not experiencing symptoms. And that's really important because we know that our data has shown us that over the last 12 plus months, that people very often have tested positive but not had symptoms. And so this is a real reflection of what people will experience at large. And every week, we use a number of modelling techniques to estimate the number of people who are testing positive for the virus. And we produce that every week. You will see it in the media and on our website every Friday lunchtime, where we provide estimates of the number of people that are testing positive for infection. But as I mentioned, we asked lots of questions. So we break that down by lots of different characteristics, so by age by region, we do it for the four countries in the UK, and so on. And we do that very much in partnership with our academic partners of which Sarah is a really, really key partner for us. Miles Fletcher So that every week when you produce the estimates, we can say not just what's going on in Scotland or England at that level, but how local can you make the data to make people aware of what's happening in, you know around the corner? Ruth Studley We're really mindful that people are interested in what's happening locally to them. So we've also been able, because we have quite a large sample, to do quite sub-regional estimates. And that has provided a granularity of information for both decision makers, but also for the general public who are interested in what's happening in their locality. The geographies that we're able to get into the detail of are, within England, about 100 sub regions to give you a feel for the size of it. Miles Fletcher Now, tell us then about the ongoing story the data have been telling us after the first wave. After that, not surprisingly, we found quite a low level of prevalence in those early readings. But what was the story from then on, what happened after that? And what have been the key moments from an analyst's point of view do you think in the path of this pandemic? Ruth Studley That's an interesting question. Over the course of the autumn last year, we did start to see a general steady rise, or just before Christmas with the identification of the Alpha variants as we now know it. And an awful lot of work went into that because as part of the swabs that we take and the analysis we do, we are able to do additional analyses to try to identify different variants and that is absolutely critical. There were some key points there obviously, because our information was part of the suite of information that government uses to help make their decisions around all the different interventions that they wanted to put in place, such as the different lockdowns across the UK. So the infection rate was steadily rising, and it peaked in January 2021. All of the days over the last 18 months have very much gone into one, but it peaked in January 2021. And then we started to see a steady decrease over the next couple of weeks and months with various different interventions occurring and then obviously we saw the arrival of Delta variant, and that has had an impact. And within certainly months, if not weeks of identification of that it became the dominant variant across the UK. And we are now seeing that the data has increased. Miles Fletcher And as you say, it's the Delta virus that really changed things suddenly midway, if you like, through the pandemic. Sarah, would you say that that's been the most important finding of the study so far? Professor Sarah Walker Well, I mean, I think it's easy to focus on Delta. But you know, frankly, Alpha was pretty terrible in December. I think it's actually been incredible to think that, frankly, in the space of only six months, the virus went through two such massive changes, which basically doubled transmissibility every time. So Alpha was twice as transmissible and Delta was twice as transmissible again. Of course, what is different is that we now have vaccinations and I think that is somewhere where the survey is increasingly really making a major contribution, because linked data is really brilliant and we can do a lot of stuff with it. But we're not really able to adjust very well with the kind of large scale NHS linked data, for characteristics that do affect people's chance of testing positive, whereas in the survey, because as researchers we collect this detailed information every month, we're able to adjust for things like whether people are healthcare workers, when they work in care homes, smoking status. Things that actually do make a difference to your risk of testing positive: whether they have been to a hospital. And so we're able to get much better estimates of the impact of vaccines on infection rates, really in the community, than many of these other big studies. Of course, we can't do it all, we can't look at hospitalizations, because they're quite rare in our study, but we can actually make a really big contribution. Miles Fletcher And that's all because the study worker as well as taking the taking the test sample sits down and actually goes through the questions with gets a lot more information from them. Sarah Walker Absolutely. And then also at the antibody testing, which we're now doing on around a half of our participants who are giving us finger prick blood every month, and that's enormously valuable in tracking levels of antibody protection in the community as a whole and then trying to understand how that relates to infection rates in different age groups and different parts of society. Miles Fletcher And that's the particular value of testing the same group of people again, and again. Sarah Walker And actually also because it turns out that one of the really fascinating findings is that people who've had COVID before, if they get vaccinated they do even better. But in order to find that out, you need to know who's been infected before. And because we've been testing our participants every month, some people now for nearly 18 months, we have a really good history. We won't catch every single infection but for most people we have a really good idea about who's had COVID or not. And again, that allows us to make much better estimates of the impact of vaccination, the impact of natural infection, and then how the two work together. Miles Fletcher And that's because the survey has covered the period right before the introduction of the of the vaccines right through their mass rollout. And according to the data you produce, towards the end of the summer, we're starting to actually see some of that vaccine induced positivity actually reducing once again, and new questions arise about booster jobs and so forth. What remains to be learned about the effect of those vaccines and about the longer-term impacts of COVID more generally? Sarah Walker There's a really huge emphasis on boosters at the moment, Miles, and I understand from the point of view of individual people, particularly if they are having their antibodies tested, and they see it go positive to negative, they may feel some concern, but it's really important to understand that the immune system has got memory. And actually you can have low levels of antibodies, but actually, the immune system remembers, and if you get exposed to COVID again, you get a burst of activity, and you are actually protected, particularly from hospitalization and death. And ultimately we've got to find a way to live with this virus, we aren't going to eliminate it and we can't keep vaccinating 50 million people a year. And so what we're trying to do as we move forward is to stop people ending up in hospital and stop them dying, whilst understanding that the virus is going to be with us. And I think the survey has really got a crucial role in answering some of the questions around what kind of levels of background infection can we live with. Are there thresholds of background infection, which then do trigger increases in hospitalizations, which obviously we can't live with? You know, who actually needs boosting in order to stop them ending up in hospital, as well as who maybe needs boosting in order to stop them getting infection, but infection that particularly leads to bad consequences. Obviously, antibodies are only part of the picture, we also have T cells and other things that help protect us from infection. I think over the next six months, the survey will really help us unpick some of those answers and really, it's about helping us learn how to live with this, because we aren't going to get rid of it. It's still a brand new virus. I mean, 18 months ago, we didn't know it existed. The beginning of March 2020, there was stuff in the papers about this virus in this Chinese city, but no one had any idea. And no, we still have a huge amount to learn. And the survey can really, really help. Miles Fletcher Vital then, that it keeps going. It's one thing I've discovered in working on the media side of ONS, and like everything at ONS we try and show with numbers, it's interesting how media attention for our estimates goes up and down according to the level of infection. Is there a danger more broadly do you think then that people might think at this stage that we're seeing deaths and hospitalisations thankfully at fractional levels of what they were before, but people might still think that it's all over really, that we don't need to take this as seriously as we did, and Ruth how do we get the message out about the importance, the continuing importance of trusting the data? Ruth Studley So Miles I think one of the key things, you talked about the benefits of the longitudinal aspects of the survey, going back to the same people week in, week out. One of the critical benefits of this survey has been our ability to respond and be relevant to what decision-makers need. Sarah's done some fantastic work and I'll let her talk about the work that she's done around vaccine effectiveness, but actually being able to understand and pre-empt and work with our users to understand what is critically needed is one of the real benefits of this survey. Because not only do you have that breadth of data and that wealth of data, but being able then to link it across ONS to some of our other data sources, whether that is the immunisation data or other data sources that we might hold within ONS, all adds a huge amount of value. Miles Fletcher Sarah, just looking at that international dimension again, are other countries running studies like this? Sarah Walker So, to my knowledge there isn't another study like this in the world, both in terms of its length and the fact that it has been going since April 2020, but also in particular its size and representativeness of the general population. Generally what other studies are doing is relying on testing data, so relying on linking information about people who come forward to be tested in national testing programmes, either because they have symptoms or other reasons like workplaces. And of course, whilst that data is very powerful and is very large, not everyone who has symptoms takes a test and certainly there are plenty of people who have Covid without symptoms who never know they need a test. So, you know there are some real limitations of using that data, so from that point of view the survey really has got huge benefit and that benefit is recognised by policy bodies including the WHO in terms of particularly informing questions around vaccine effectiveness where being able to do the kind of adjustments that we do is really so important. Miles Fletcher So the survey has established itself as well, what the Times no less calls the most reliable measure of infection rates provided by the UK government. That speaks loudly because the media in the UK don't hand out compliments for nothing: that's a powerful testimony to how this study has established itself and it remains central to the UK's research effort, and we're told is to some degree unique in the world. Thank you to all three of our guests Tina Thomas, Head of Survey Operations, Ruth Studley Head of Analysis and from Oxford Professor Sarah Walker. Next time we hear the inside story of the 2021 Census and hear about the challenge of getting responses from every household in England and Wales during a period of national lockdown. You can subscribe to new episodes of this podcast on Spotify, Apple Podcasts and all the other major podcast platforms. You can also get more information by following the @ONSfocus Twitter feed. The producers of Statistically Speaking are Elliot Cassley and Julia Short, I'm Miles Fletcher, goodbye.

Statistically Speaking is the Office for National Statistics' regular monthly podcast, offering in-depth interviews on the latest hot topics in the world of data, taking a peek behind the scenes of the UK's largest independent producer of official statistics and exploring the stories behind the numbers.