Comparing the Capability of Two Processes Using C(pm)

Summary: [This abstract is based on the authors' abstract.] In process capability assessment, the C(p) and C(pk) indices do not take into account the proximity of the process mean to the target value of the process characteristic as does the C(pm) index. Four methods of obtaining approximate confidence intervals are proposed, one based on the Boyles statistical theory and three based on the bootstrap. Performances are compared in two independent and normal process environments.