%0 Journal Article
%T An Enhancement for the Multivariate EWMA Chart
%A Michael B.C. Khoo
%A S.J. Gun
%J Matematika
%D 2006
%I Universiti Teknologi Malaysia
%X A quality control chart is one of the tools that is used to solve quality control problems. A control chart is used to identify the causes of a problem. Quality control for most processes involves more than one correlated variable. This is known as multivariate quality control. A multivariate EWMA (MEWMA) control chart is a good chart to detect a small shift in the mean vector of a multivariate process. This paper suggests the use of the maximum likelihood method on the MEWMA chart for the detection of the actual time of the occurrence of a permanent shift in the mean vector. The use of a time step change estimator on a MEWMA chart will benefit quality control engineers in process monitoring in industries.
%K Multivariate EWMA (MEWMA) chart
%K maximum likelihood estimator
%K time step change estimator
%K out-of-control signal
%K Type-I error.
%U http://www.fs.utm.my/matematika/images/stories/matematika/20062229.pdf