A0771
Title: A head-to-head comparative study of the conditional performance of control charts based on estimated parameters
Authors: Inez Zwetsloot - City University of Hong Kong (Hong Kong) [presenting]
Abstract: It is often of interest to detect changes in data. Statistical process monitoring (SPM) provides tools to monitor data and signal changes in the data. Three well-known tools are the Shewhart control chart, the cumulative sum (CUSUM) control chart, and the exponentially weighted moving average (EWMA) control chart. Before a control charts can be set up, estimates of the process parameters are needed. To this end, an initial data set is collected. Many researchers have shown that the resulting estimation error strongly influences the performance of these charts. However, a given amount of estimation error may differ in effect across the three control charts. Therefore, we perform a pairwise comparison of the effect of estimation error across these charts. We conclude that the Shewhart chart is more strongly affected by estimation error than the CUSUM and EWMA charts. Furthermore, we show that the general belief that the CUSUM and EWMA charts have similar performance no longer holds under estimated parameters.
