Computer program for calculating the <i>p</i>‐value in testing process capability index <i>C_pmk</i>

Abstract

Abstract Many process capability indices, including C p , C pk , and C pm , have been proposed to provide numerical measures on the process potential and performance. Combining the advantages of these indices, Pearn et al . (1992) introduced a new capability index called C pmk , which has been shown to be a useful capability index for processes with two‐sided specification limits. In this paper, we implement the theory of a testing hypothesis using the natural estimator of C pmk , and provide an efficient Maple computer program to calculate the p ‐values. We also provide tables of the critical values for some commonly used capability requirements. Based on the test we develop a simple step‐by‐step procedure for in‐plant applications. The practitioners can use the proposed procedure to determine whether their process meets the preset capability requirement, and make reliable decisions. Copyright © 2002 John Wiley &amp; Sons, Ltd.