Yeh, Arthur; Lin, Dennis; Zhou, Honghong; Venkataramani, Chandramouliswaran A multivariate exponentially weighted moving average control chart for monitoring process variability. (English) Zbl 1121.62523 J. Appl. Stat. 30, No. 5, 507-536 (2003). Summary: This paper introduces a new multivariate exponentially weighted moving average (EWMA) control chart. The proposed control chart, called an EWMA V-chart, is designed to detect small changes in the variability of correlated multivariate quality characteristics. Through examples and simulations, it is demonstrated that the EWMA V-chart is superior to the |S|-chart in detecting small changes in process variability. Furthermore, a counterpart of the EWMA V-chart for monitoring process mean, called the EWMA M-chart is proposed. In detecting small changes in process variability, the combination of EWMA M-chart and EWMA V-chart is a better alternative to the combination of MEWMA control chart (Lowry et al. , 1992) and |S|-chart. Furthermore, the EWMA M- chart and V-chart can be plotted in one single figure. As for monitoring both process mean and process variability, the combined MEWMA and EWMA V-charts provide the best control procedure. Cited in 20 Documents MSC: 62-XX Statistics PDFBibTeX XMLCite \textit{A. Yeh} et al., J. Appl. Stat. 30, No. 5, 507--536 (2003; Zbl 1121.62523) Full Text: DOI