Title: A modified MEWMA control chart: PEWMA control chart

Authors: Jian Liu; Kai-Yun Yang; Wei Wen

Addresses: State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, Hunan, China ' State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, Hunan, China ' State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, Hunan, China

Abstract: The multivariate exponentially weighted moving average (MEWMA) control chart, in which the smoothing parameter is a principal diagonal matrix, is established based on the assumption that the samples follow the standard normal distribution to monitor the multivariate quality characteristics. However, monitoring quality characteristics always exists in the whole process. To make the MEWMA control chart more effective, a modified multivariate exponentially weighted moving average control chart, namely practical MEWMA (PEWMA) control chart, is proposed, in which the smoothing coefficient matrix is extended to a full-rank matrix which the smoothing parameter are all not zero. Analysis of both the in-control and out-of-control statistical performance of PEWMA control chart illustrate that the average run length of PEMWA control chart is more superior to the MEWMA. Finally combined with a factory example, a minimisation cost model is constructed based on the Lorenzen-Vance economic model to optimise the parameter combination.

Keywords: multivariate exponentially weighted moving average; MEWMA; PEWMA control chart; statistical performance; economic model.

DOI: 10.1504/IJMCP.2017.084052

International Journal of Management Concepts and Philosophy, 2017 Vol.10 No.2, pp.184 - 198

Received: 09 Sep 2016
Accepted: 15 Jan 2017
Published online: 08 May 2017 *

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