자기출발 EWMA와 X 관리도의 관리상태 성능

초록

In monitoring a process with control charts, in-control parameters should be estimated from Phase I samples because the parameters are rarely known with certainty in practice. In general, the number of Phase I samples can often be impractically large in most applications for practitioners to be assured of having performance close to the desired performance. However, collecting the sufficiently large amount Phase I samples can be difficult in some applications. At this time, the self-starting procedure helps to monitor the process using a small amount of initial samples. This paper considers the self-starting EWMA and X charts based on the self-starting procedure used in the previous research, and evaluates the in-control perfomance of two control charts by using simulation study. The average of ARL (AARL) and the standard deviation of ARL (SDARL) are used to evaluate the in-control run length performance. From simulation results, we found that there was a significant amount of variation in the in-control performance obtained by the number of initial samples, however it was not as large as we expected.

키워드