Paper Info
Title
Enhanced EWMA charts for monitoring the process coefficient of variation
Abstract
The coefficient of variation (CV) is an important quality characteristic when the process variance is a function of the process mean for a production process. In this paper, we develop an auxiliary information-based (AIB) estimator for estimating the squared CV, along with its approximated mean and variance. This estimator is then used to devise new one-sided EWMA charts for monitoring the increases or decreases in the squared CV of a normal process, named the AIB-EWMA CV charts. In addition, the sensitivities of these control charts are also enhanced with the fast initial response feature. The Monte Carlo simulation method is used to compute the run length characteristics of the proposed CV charts. Based on detailed run length comparisons, it is found that the proposed AIB-EWMA CV charts are uniformly and substantially better than the existing EWMA CV charts when detecting different kinds of upward/downward shifts in the squared CV. The proposed charts are also applied to a real dataset to support the proposed theory.
Year
DOI
Venue
2020
10.1002/qre.2710
QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL
Keywords
DocType
Volume
auxiliary information,average run length,EWMA,coefficient of variation,control chart,Monte Carlo simulation,statistical process control
Journal
36.0
Issue
ISSN
Citations 
7.0
0748-8017
0
PageRank 
References 
Authors
0.34
0
3
Name
Order
Citations
PageRank
Abdul Haq16318.42
Nazish Bibi200.34
Michael B. C. Khoo328249.97