Performance Comparison of the Run Sum t , EWMA t and Standard t Control Charts

—The t-chart is a rare event chart, where a rare event chart is a control chart that provides information about a process when the data comes from rarely occurring events. In this paper, a comparison of the performances of several t type control charts, like the run sum t chart, exponentially weighted moving average (EWMA) t chart and standard t chart are compared based on the average run length (ARL) criterion. The results show that among the t type charts considered, the run sum t chart gives smaller ARL values and is more sensitive than the EWMA t chart for detecting medium to large shifts in the process mean. The EWMA t chart is more sensitive than the run sum t chart for detecting small mean shifts. However, the standard t chart has the largest ARL compared with the run sum t chart and the EWMA t chart.