Poka-yoke is a Japanese term meaning mistake proofing. It is a device or design feature that prevents an error from happening, or detects it immediately so it cannot become a defect. Shigeo Shingo developed the approach at Toyota.
Prevention and detection
- Prevention: the error cannot be made — a part that only fits one way, a form that cannot be submitted with a missing field.
- Detection: the error is caught at once — a sensor stops the line if a component is missing, a scale rejects an underweight pack.
Everyday examples
- A car that will not start unless it is in park
- Plugs and connectors shaped to fit only the right socket
- Banking systems that validate account numbers before a transfer
- Pharmacy software that alerts on dangerous drug interactions
How to find poka-yoke opportunities
Review defect data and complaints, find the step where the error originates, ask why the error is possible, and design the simplest, cheapest device that makes it impossible or immediately visible. Simple solutions — guides, jigs, colour codes, checklists built into software — are usually the most robust.
