A generally weighted moving average control chart for monitoring the coefficient of variation

This paper proposes a generally weighted moving average control chart with adjusted time-varying control limits for monitoring the coefficient of variation of a normally distributed process variable. This control chart is constructed by combining the generally weighted moving average procedure with a resetting model.The implementation of the proposed chart is presented. Some numerical comparison of the proposed chart with several relevant competing control charts is performed. In general, as demonstrated by extensive simulation results, our chart is clearly more sensitive than other competing procedures for each combination of the in-control target value of the coefficient of variation, the sample size and the shift size. Detection examples are given for two industrial manufacturing processes to introduce the proposed control chart.