Monitoring Coefficient of Variation Using CUSUM Control Charts

In the field of statistical process control, the cumulative sum (CUSUM) control chart is used as a powerful tool to detect process shifts. One of the main features of the CUSUM control chart is that it takes into account the past information at each sampling time of the process. Recently, the rapid development of optimization algorithms and software makes the CUSUM chart easier to be implemented. As a result, the CUSUM control chart has been increasingly applied widely. The goal of this chapter is to present some recent innovative CUSUM control charts monitoring the coefficient of variation (CV). We address several problems related to the CUSUM chart monitoring the CV. The first section provides important definitions of a CUSUM control chart, including the CUSUM sequence, the CUSUM statistics, the implementation of a CUSUM control chart, the average run length (ARL), and the expected average run length (EARL). In the second section, we investigate the effect of measurement error on the CUSUM control chart CUSUM control chartmeasurement error onmonitoring the CV. Finally, a fast initial response strategy to improve the performance ofCUSUM control chartperformance of the CUSUM control chart is presented.