Poka-Yoke (Mistake-Proofing)

Poka-yoke, associated with Shigeo Shingo's manufacturing work, designs a specific error out of a process or makes it detectable before it propagates. It does not make all mistakes impossible.

Poka-yoke targets a specific error at the point where it can occur or propagate. A shaped fixture can prevent an incorrect assembly; a count or signal can reveal an omission before work proceeds. Prevention and detection are different functions, and neither makes a whole process infallible. A control must match the actual error mechanism.

Begin with a recurring mistake and identify what information or constraint would change it. A required field prevents a blank submission, but cannot ensure that the entered answer is true. Test both the targeted mistake and legitimate exceptions. Prevention may be preferable in one case, while detection or recovery is more proportionate in another; the choice depends on consequences and cost.

When to use it

When the same errors keep recurring despite training; when the cost of errors is high and the causes are simple; when designing systems, processes, or products that will be used by humans (who will inevitably make mistakes); when simplifying error-prone procedures.

How it can help

Identify the exact error mechanism, choose an appropriate constraint or signal, and test legitimate exceptions. A required field prevents omission but does not establish correct content.