Control Chart is a graphical tool used to determine process performance with time. These were developed by Walter A. Shewhart and hence are also known as Shewhart charts. These charts help determine whether the process is stable or not. If the process is stable, the process will only have inherent variation (Common Cause variation). The region of common cause variation is given by Control limits (Upper and Lower control limits). Any process variation outside these limits is considered as Special Cause Variation.
Mistake Proofing or Poka Yoke - is a technique for eliminating errors by making it impossible to make mistakes in the process. It is often considered the best approach to process control.
It works on the principle - "It is good to do it right the first time. It is even better to make it impossible to do it wrong the first time".
Mistake Proofing can be preventive (prevent the error from occurring) or detective (detect the error if it happens) in nature and is usually implemented in one of the following ways.
1. Warning: audio and/or visual warning either before the error occurs or after it has occurred.
2. Control: errors are not possible or even if an error occurs, it is not allowed to move to the next step.
3. Shutdown: machine or process shutdown when an error is about to happen or as soon as an error occurs.
An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Prashanth Datta on 22nd February 2019.
Applause for all the respondents- Prashanth Datta, Tarun Gupta
Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.