Title

Obtaining Confidence Intervals For Cpk Using Percentiles Of The Distribution Of Ĉp

Keywords

Inverse chi-square; Process capability index; Simulation

Abstract

Ĉpk is used as an estimate of process capability and can reflect performance degradation due to both shifts in the process mean and variability. Exact upper and lower confidence limits for the actual parameter value are elusive. Objections to existing estimators focus on two areas: the difficulty of executing the needed computations and the excessive widths of those confidence bounds. The CPE estimator (so called since it relies on Ĉp) which we derive in this paper is formed by simply multiplying Ĉpk by a value from the inverse chi-square distribution. A PASCAL computer program is supplied which generates those percentiles. Our CPE is compared via simulation to other estimators and is shown to be the preferred selection in most cases by providing the requisite probability coverage and narrow interval widths.

Publication Date

3-1-2001

Publication Title

Quality and Reliability Engineering International

Volume

17

Issue

2

Number of Pages

113-118

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/qre.389

Socpus ID

0035273023 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0035273023

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