A New Measure of Process Capability:<i>C_pm</i>

Abstract

A new measure of the process capability (Cpm) is proposed that takes into account the proximity to the target value as well as the process variation when assessing process performance. The sampling distribution for an estimate of Cpm (Ĉpm) and some of its properties have been examined and an example of its application is included. The new index is easy to compute and, with the aid of the included tables, easy to analyze. Ĉpm has some more desirable statistical properties than Ĉp and Ĉpk, the estimates of the Cp and Cpk indices, respectively.