Title: Attribute control charts for monitoring the covariance matrix of bivariate processes.
Authors: Machado, M. A. G.; Ho, L. L.; Costa, A. F. B.
Abstract: Abstract: In this article, we consider the use of 3 attribute charts—the npxy, the npw and the Max D charts—to control the covariance matrix of bivariate processes. In comparison with the generalized variance |S| chart, the 3 attribute charts signal faster, with smaller samples, all kind of disturbances, except when the 2 variables are highly correlated. To compete with the VMAX chart, the Max D chart needs larger samples, but no more than twice bigger. An example illustrates the monitoring of the covariance matrix using the Max D and npw.
Subjects: QUALITY control charts; COVARIANCE matrices; ANALYSIS of covariance; BIVARIATE analysis; STATISTICS
Publication: Quality & Reliability Engineering International, 2018, Vol 34, Issue 2, p257
ISSN: 0748-8017
Publication type: Academic Journal
DOI: 10.1002/qre.2253

Attribute control charts for monitoring the covariance matrix of bivariate processes.

Machado, M. A. G.; Ho, L. L.; Costa, A. F. B.