MULTIVARIATE PROFILE CHARTS FOR STATISTICAL PROCESS-CONTROL

The multivariate profile (MP) chart is a new control chart for simulta neous display of univariate and multivariate statistics. It is designe d to analyze and display extended structures of statistical process co ntrol data for various cases of grouping, reference distribution, and use of nominal specifications. For each group of observations, the sca led deviations from reference values are portrayed together as a modif ied profile plot symbol. The vertical location of the symbol is determ ined by the multivariate distance of the vector of means from the refe rence values. The graphical display in the MP chart enjoys improved vi sual characteristics as compared with previously suggested methods. Mo reover, the perceptual tasks required by the use of the MP chart provi de higher accuracy in retrieving the quantitative information. This gr aphical display is used to display other combined univariate and multi variate statistics, such as measures of dispersion, principal componen ts, and cumulative sums