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New Insights into the Decisional Use of Process Capability Indices via Hypothesis Testing
Author(s) -
Lepore Antonio,
Palumbo Biagio
Publication year - 2015
Publication title -
quality and reliability engineering international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 62
eISSN - 1099-1638
pISSN - 0748-8017
DOI - 10.1002/qre.1713
Subject(s) - process (computing) , computer science , sample (material) , comprehension , sample size determination , order (exchange) , significance testing , statistical hypothesis testing , reliability engineering , mathematics , statistics , engineering , economics , chemistry , finance , operating system , chromatography , programming language
Process capability indices C p , C pk , and C pm are still nowadays widely used in industry—thanks to their easy formulation and implementation. This paper aims to give new mathematical insights in order to support their use in decision‐making via hypothesis testing. The minimum sample size usually needed in the applications to achieve fixed significance level and power is reported in light of the new mathematical aspects for C pk and C pm , which avoid misleading conclusions and the use of extensive numerical experiments. In addition, power curves for C pk and C pm , which have not previously appeared in the literature before, are also presented. Lastly, easy‐to‐follow diagrams for hypothesis testing with C pk and C pm and two critical scenarios for C pm are included in the paper to facilitate the applicative use and the comprehension of the novel inferential aspects. Copyright © 2014 John Wiley & Sons, Ltd.