Title: Bootstrap confidence limits for the process capability index C_pmk

Authors: S. Balamurali

Addresses: Department of Mathematics, Kalasalingam University, Krishnan koil 626 126, TN, India

Abstract: Process capability indices are widely used by quality professionals to determine whether a production process is capable of producing items within a specified tolerance. The capability index C_pmk is a generalised version of the basic process capability indices C_p, C_pk and C_pm. Recently, techniques and tables were developed to construct confidence limits for each index. These techniques are based on the assumption that the underlying process is normally distributed. However, many processes can be frequently skewed or heavy tailed in practice and hence the interval estimation technique that is free from the assumption of distribution is desirable. In this article, the capability index C_pmk is considered and its confidence limits are estimated using the bootstrap technique. A simulation using three distributions (one normal and two non-normal) is conducted and a comparison is made to show the performances of the three bootstrap confidence intervals.

Keywords: bootstrap method; confidence limits; process capability indices; PCIs; normal process; non-normal process; simulation.

DOI: 10.1504/IJQET.2012.046156

International Journal of Quality Engineering and Technology, 2012 Vol.3 No.1, pp.79 - 90

Published online: 30 Aug 2014 *

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