Adding an inspection can find an error after it occurs. A mistake-proofing proposal asks whether the process can prevent the error or make it immediately evident.
ASQ describes mistake-proofing as the use of methods or devices to prevent errors or make them obvious. ASQ — mistake proofing.
Define the error mechanism
Identify the specific action or condition that creates the error. A broad instruction to be more careful is not a process feature. For an illustrative assembly task, ask whether identification, orientation or sequence can be made less ambiguous.
Test the proposed control
Check the intended condition and foreseeable exceptions. A control that works only when the operator already knows the right answer may provide less protection than expected. Document how a detected exception is handled.
Mistake-proofing should support, rather than replace without evidence, the applicable control plan. Verify its actual effect and consider whether it introduces another failure opportunity before extending it to other products.
Source reviewed 25 October 2026. Practical interpretation and original illustrations by PLUSHIP / Qunhe; examples are illustrative.
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