Abstract: A variables control chart that can be used to monitor location and scale on a single chart is proposed. The procedure provides an alternative to the boxplot style of simultaneous control charts with the added advantage 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 limits analogous to the Shewhart limits are developed and several properties are investigated. The procedure is extended to the multivariate case and examples illustrating both the univariate and multivariate cases included.
Key words and phrases: Multivariate control chart, process control, simultaneous control chart.