A New Measure of Process Capability:Cpm

Abstract

A new measure of the process capability (C_pm) 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 C_pm (Ĉ_pm) 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. Ĉ_pm has some more desirable statistical properties than Ĉ_p and Ĉ_pk, the estimates of the C_p and C_pk indices, respectively.