Bootstrap confidence limits for wright'C₅

Abstract

The process engineer wants to estimate an accurate process capability index (PCI) since he wants to decide whether the process is capable or not. If it is greater than or equal to the value 1, the process is considered capable. Confidence limit plays a major role for correct interpretation of PCIs. Pearn and Chang(l997) have studied the performance of Wright's C₅ under some skewed distributions, and showed that the percentage bias of the estimator increases as the skewness coefficient θ increases.

Keywords:

• Process capability index
• Skewness coefficient
• Nonparametric
• Log-normal distribution