Normal Curves: Sexy Science, Serious Statistics

Bonus: Pheromones with commentary

Jan 26, 2026

They revisit the sweaty T-shirt study that spawned pheromone parties and DNA-based dating fads. They unpack HLA/MHC genes and how scent was used to suggest mate choice. Statistical curiosities pop up: bar chart misuse, correlated observations, within-person designs, and post-hoc subgrouping. They trace failed replications, lost data, and a meta-analysis that questions the original claims.

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ADVICE

Don't Use Bar Charts For Numerical Data

Always report numeric summaries and avoid using bar charts for numerical data because they hide distribution and force readers to guess.
Provide means, sample sizes, and variability so others can replicate and assess results.

INSIGHT

Why Correlated Observations Matter

Correlated observations arise when multiple measurements originate from the same unit, e.g., multiple shirt ratings per woman.
Ignoring these dependencies inflates apparent sample size and risks misleading significance.

INSIGHT

Three Sources Of Dependency In The Study

The sweaty t-shirt data had three dependency sources: multiple shirts per woman, paired (within-woman) comparisons, and men rated by multiple women.
Wedekind averaged replicates and paired correctly but failed to account for correlations by man, risking one man's ratings dominating results.

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While we’re on a short break between seasons, we’re revisiting some of our favorite episodes from Season 1. This week, we’re re-releasing our debut episode on pheromones and sexy sweat, with some added commentary up front..

Sweaty t-shirt dating parties, sex pheromone dating sites, choosing your dating partner by sniffing them up — wacko fringe fads or evidence-based mating strategies? And what does your armpit stain have to do with your kids’ immune systems, or hormonal contraceptive pills, or divorce rates?

In this episode, we reach back into the 1990s and revisit the scientific paper that started it all: The Sweaty T-Shirt Study. They bring a sharp eye and open mind, critically examining the study and following the line of research to today. Along the way, they encounter interesting statistical topics – including correlated observations, within-person study design, and bar chart blasphemy – with a short, surprising detour into Neanderthal sex.

Statistical topics

Bar charts
Correlated observations
Cherry-picking
Data and methodological transparency
Multiple testing
Post-hoc analyses
Unit of observation / unit of anaysis
Within-person study design

Methodological morals

“Repeat after me: Bar charts are not for numerical data.”

“Those who ignore dependencies in their data are destined for flawed conclusions.”

References

Nuzzo, R. Ah, Love at first whiff. Los Angeles Times. May 19, 2008.
Papamarko, S. Pheromone parties attempt to match singles by scent. Yahoo!life. April 12, 2012.
Sainani, K. Stone Age Gene Swap. Stanford Magazine. November/December 2011.
Aldhous, P. Darling, You Smell Wonderfully Different. New Scientist. 6 May 1995.
Wedekind C, Seebeck T, Bettens F, Paepke AJ. MHC-dependent mate preferences in humans. Proc Biol Sci. 1995; 260(1359):245-249. doi:10.1098/rspb.1995.0087
Hedrick P, Loeschcke V. MHC and mate selection in humans?. Trends Ecol Evol. 1996;11(1):24. doi:10.1016/0169-5347(96)80237-0
Wedekind C, Seebeck T. Reply from C. Wedekind and T. Seebeck. Trends Ecol Evol. 1996;11(1):24-25. doi:10.1016/0169-5347(96)81061-5
Wedekind C, Füri S. Body odour preferences in men and women: do they aim for specific MHC combinations or simply heterozygosity?. Proc Biol Sci. 1997;264(1387):1471-1479. doi:10.1098/rspb.1997.0204
Havlíček J, Winternitz J, Roberts SC. Major histocompatibility complex-associated odour preferences and human mate choice: near and far horizons. Philos Trans R Soc Lond B Biol Sci. 2020;375(1800):20190260. doi:10.1098/rstb.2019.0260

Kristin and Regina’s online courses:

Demystifying Data: A Modern Approach to Statistical Understanding

Clinical Trials: Design, Strategy, and Analysis

Medical Statistics Certificate Program

Writing in the Sciences

Epidemiology and Clinical Research Graduate Certificate Program

Programs that we teach in:

Epidemiology and Clinical Research Graduate Certificate Program

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Kristin - LinkedIn & Twitter/X

Regina - LinkedIn & ReginaNuzzo.com

(00:00) - Introduction
(06:09) - Conclusion
(06:16) - Breaking Down the Original Sweaty T-Shirt Study
(06:16) - Study Design Flaws and Data Transparency Issues
(06:17) - Media Reactions and the Study’s Public Impact
(06:26) - The Pill's Influence on Scent Preferences
(06:30) - Analyzing the Study's Questionable Results
(06:30) - Other Studies and their results
(06:34) - Overstated Conclusions and Wandering Discussions
(06:35) - Pheromone Dating Parties
(06:39) - Statistical Flaws: Correlated Observations Explained
(06:55) - The Science of HLA Genes and Mate Selection
(07:05) - Pheromone Dating Sites and Genetic Matching