Six Sigma Green Belt Certification Practice Exam

Which of the following is an example of mistake-proofing?

1. Using an Xbar and R chart to prevent errors

2. Using 100% inspection to detect and contain defects

3. Using color coding as an error signal

4. Having the team that created the errors repair them

The correct answer is: Using color coding as an error signal

Using color coding as an error signal exemplifies mistake-proofing, also known as "poka-yoke." This practice involves designing processes or systems in a way that minimizes the chances of human error or makes it easy to detect and correct mistakes. Color coding serves as an intuitive visual cue that helps individuals easily identify correct procedures, components, or paths, thereby reducing the likelihood of errors occurring. The other options, while related to quality control, do not embody the principle of mistake-proofing as clearly. For instance, using an Xbar and R chart is primarily a statistical process control tool aimed at monitoring process variation and not specifically designed to prevent errors before they occur. Similarly, 100% inspection focuses on identifying defects after they have occurred rather than preventing them in the first place. Finally, having the team that created the errors repair them may not effectively address the underlying causes of the errors, nor does it incorporate a preventative measure to avoid future mistakes.