Fast initial response for CUSUM quality-control schemes: Give your CUSUM ahead start

The fast initial response (FIR) feature for cumulative sum (CUSUM) quality- control schemes permits a more rapid response to an initial out-of-control situation than does a standard CUSUM quality-control scheme. This feature i s especially valuable at start-up or after a CUSUM has given an out-of-cont rol signal. This article presents the average run length and the distributi on of run length for CUSUM schemes with the FIR feature and compares FIR CU SUM schemes to standard CUSUM schemes. The comparisons show that if the pro cess starts out in control, the fast initial response feature has little ef fect; however, if the process mean is not at the desired level, an out-of-c ontrol signal will be given faster when the FIR feature is used.