Beyond Deming Kingman's Equation – John Bicheno
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Sep 23, 2025 
John Bicheno, lean scholar and educator who ran an MSc in Lean and directed research at LERC, unpacks Kingman’s Equation. He discusses how utilisation nonlinearly inflates queues. He illustrates with motorway traffic, a dice game, batching, arrival and process variation, and tactics like scheduling and setup reduction to smooth flow.
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Reduce Arrival Variation As Well As Process Variation
- Address arrival variation as well as process variation because Kingman's equation weights them equally.
- Bicheno warns Six Sigma focuses on process but neglects arrival patterns which can be cheaper to influence.
Use Access Control To Smooth Arrivals
- Manipulate arrival patterns to smooth demand using speed limits or ramp metering analogues.
- Bicheno notes traffic engineers reduce average speed and use access-control lights to lower arrival variation and prevent jams.
Marketing Batches Flooded The Call Centre
- A bank's marketing batch-sent mail to get postage discounts and caused call centres to be overwhelmed.
- James Lawther recounts that concentrated mailings created feast-or-famine demand that flooded the contact centre.
