Which of the following is an example of mistake-proofing? Please choose the correct answer.

Question

Options

• AUsing x and R chart to prevent errors
• BUsing 100% inspection to detect and contain defects
• CUsing color coding as an error signal
• DHaving the team that created the errors repair them

• A
  2% (1)
• B
  11% (5)
• C
  80% (37)
• D
  7% (3)

Explanation

Color coding as an error signal exemplifies mistake-proofing (poka-yoke) - a technique that physically or visually prevents errors from occurring or immediately flags them before they become defects, requiring no inspection or data analysis.

Why the distractors are wrong:

• A (x-bar and R charts): These are statistical process control tools used to monitor variation after the fact, not prevent errors at the source.
• B (100% inspection): Inspection detects defects after they've already been made - it never prevents the error from occurring in the first place.
• D (team repairs their own errors): This is accountability or rework, not prevention - the error has already happened.

Memory tip: Think of poka-yoke as "idiot-proofing" - the system itself stops the mistake before it can happen (e.g., a USB plug that only fits one way, or a color-coded wire that can't be connected to the wrong terminal). If a human still has to find the mistake, it's not poka-yoke.

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