Estimation of Process Capability Index Using Confidence Intervals of Process Parameters

Abstract

The conventional process capability index (PCI) is a measure of process performance whose value depends on the process mean (), standard deviation () and the specified tolerance. The point estimates of  and  are used to estimate the PCI. In this paper, a new PCI is proposed by utilizing the 100(1-)% Confidence Intervals (CI) for both  and . This has led to nine possible estimates of PCI which are combined through a weighted average and three different methods of weights are proposed. The new estimator is shown by simulated experiments that the new estimator is more consistent than the classical point estimate of PCI.

Keywords: Confidence Interval (CI), Process Capability Index (PCI), Specification Limits, Super structure

Cite this Article

Sai Sarada Vedururu, M. Subbarayudu, K.V.S. Sarma. Estimation of Process Capability Index Using Confidence Intervals of Process Parameters.  Research & Reviews: Journal of Statistics. 2018; 7(3): 49–57p.