Estimation of capability index based on bootstrap method

Abstract A process capability index Cpmk is recently proposed to measure the degree of process capability of a system. Cpmk is a generalized version of the existing indices Cp, Cpk, and, Cpm, which have been studied extensively in the last few years. In this paper, we present the estimators of Cpmk and derive its asymptotic distribution. We also utilize the asymptotic variance of the estimator of Cpmk to derive the two-sided confidence interval for Cpmk based on a percentile-t bootstrap method. Our new confidence intervals are shown to outperform the ones based on the percentile and standard bootstrap method by simulation.