Title: Testing process performance based on capability index C-pk with critical values
Authors: Pearn, WL
Lin, PC
Department of Industrial Engineering and Management
Issue Date: 1-Dec-2004
Abstract: Process capability index C-pk has been widely used in the manufacturing industry as a process performance measure. In this paper, we investigate the natural estimator of the index C-pk, and show that under the assumption of normality its distribution can be expressed as a mixture of the chi-square and the normal distributions. We also implement the theory of hypothesis testing using the natural estimator of C-pk, and provide efficient Maple programs to calculate the p-values as well as the critical values for various values of alpha-risk, capability requirements, and sample sizes. The behavior of the p-values and critical values as functions of the distribution parameters are investigated to obtain tight critical values for reliable testing. Based on the test, we develop a simple and practical procedure for in-plant applications. The practitioners can use the proposed procedure to determine whether their process meets the preset capability requirement, and make reliable decisions. (C) 2004 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.cie.2003.03.001
ISSN: 0360-8352
DOI: 10.1016/j.cie.2003.03.001
Volume: 47
Issue: 4
Begin Page: 351
End Page: 369
Appears in Collections:Articles