A Simultaneous Control Chart

Abstract

A new process control chart, designated the simultaneous control chart, is introduced. Through the use of resistant measures and a modified box plot display, this single chart controls the process level and variability and also supplies information about the process distribution and specifications. It is argued that the simultaneous control chart provides more effective information for decision making than x̄ and R charts since it is (1) more robust against distributional assumption violations and (2) more transparent to the nonstatistical user.