A General Approach For Testing The Process Capability Index

This paper presents a generalized approach to the problem of testing with the process capability index Cĉp. It allows for testing at any α‐level and any sample size. For small sample sizes n \u3c 30, n odd, tables are included with αs incremented by 0.025, which are generated by a computer program. This program is written in BASIC and appears in an Appendix. For different α levels (say α = 0·1) the program can be used to generate the appropriate value to use in determining the critical values. For larger sample sizes an approximation method is supplied. Additionally, the method to derive an associated operating characteristic curve is examined. Copyright © 1993 John Wiley & Sons, Ltd