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Article

A multivariate adaptive control chart for simultaneously monitoring of the process parameters

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Pages 2031-2049 | Received 31 Jan 2022, Accepted 01 Apr 2022, Published online: 22 Apr 2022
 

Abstract

There have been some advances in multivariate control charts in recent years. This paper presents a new simultaneous scheme for monitoring both the mean and variability of a multivariate normal process in a single chart, which is developed by improving and modifying another recently proposed scheme. We not only propose a new control scheme but also make it adaptive by varying all control chart parameters. Our scheme, for the first time, considers the process variability in two forms: “covariance matrix” and “multivariate coefficient of variation (MCV)”. This scheme, again for the first time, considers simultaneous monitoring of the MCV with another process parameter (in our case, the mean vector). In addition, we develop a Markov chain model to compute the average run length and average time to signal values. We conduct extensive numerical analyses to measure the performance of the proposed scheme in two scenarios of process variability. At last, we present a numerical example by using a real dataset from a healthcare process to illustrate how the scheme can be implemented in practice.

Acknowledgments

The authors thank the journal’s editorial board and the reviewers for their constructive comments, which have led to significant improvements in the quality of the paper.