Whats the difference between process capability and process performance statistics?
Process capability statistics, like cp and cpk, only take into account short term process variation. Consequently, they will give overly optimistic values when the process is actually drifting. Process performance statistics consider both short term and long term variation so they tend to be more representative of the true quality of the process. Consider cp and cpk to be the goal for Pp and Ppk, respectively, which would happen when the process is brought into statistical control.
Related Questions
- Since process capability/performance statistics are sensitive to so many conditions, aren there alternative methods available for evaluating a process that are more robust?
- What conditions must be satisfied to validate process capability/performance statistics?
- Whats the difference between process capability and process performance statistics?
