Some new methods for comparing the capability of two processes using process capability index Cpm. Issue 5 (24th June 2021)

• Record Type: Journal Article
• Authors: Perakis, Michael
• Is Part Of: International journal of quality & reliability management. Volume 39:Issue 5(2022)
• Page Start: 1170
• Page End: 1189
• Publication Date: 2021-06-24
• Subjects: Process capability indices -- Confidence intervals -- Non-central chi-square distribution -- Non-central F distribution -- Doubly non-central F distribution; Quality control -- Periodicals; 658.562
• DOI: 10.1108/IJQRM-01-2021-0012
• Languages: English
• ISSNs: 0265-671X

Abstract

Abstract : Purpose: The purpose of the paper is the construction of confidence intervals for the ratio of the values of process capability index C pm for two processes. These confidence intervals can be used for comparing the capability of any pair of competitive processes. Design/methodology/approach: Two methods for constructing confidence intervals for the ratio of the values of process capability index C pm for two processes are proposed. The suggested techniques are based on a two-step approximation of the doubly non-central F distribution. Their performance is tested via simulation. Findings: The performance of the suggested techniques seems to be rather satisfactory even for small samples, as illustrated through the use of simulated data. Practical implications: The practical implication of the suggested techniques is that they can be implemented in real-world applications, since they can be used for comparing the capability of any pair of competitive processes. Originality/value: The paper presents two new methods for constructing confidence intervals for the ratio of the values of process capability index C pm for two processes.