AN ALTERNATE VARIABLES CONTROL CHART - THE UNIVARIATE AND MULTIVARIATE CASE

A variables control chart that can be used to monitor location and sca le on a single chart is proposed. The procedure provides an alternativ e to the boxplot style of simultaneous control charts with the added a dvantage of performing equally well for both large and small subgroup sizes. The resulting control chart provides information regarding the process's proximity to the target value and its variability. Control l imits analogous to the Shewhart limits are developed and several prope rties are investigated. The procedure is extended to the multivariate case and examples illustrating both the univariate and multivariate ca ses included.