关键词: 统计过程控制, t控制图, 平均运行链长

Abstract: Aiming at the inaccuracy estimation of process variance,statistic t was used to substitute statistic ,and a Side-sensitive Conforming Run Length t (SCRL&t) chart was proposed to monitor the process mean.The transition probability matrix of SCRL&t chart was constructed with Markov chain method,and the corresponding Average Run Length (ARL) was given.The optimal parameters of SCRL&t chart were obtained through optimizing the out-of-control ARL while keeping the in-control ARL constant.The simulation results showed that the performance of SCRL&t chart was better than the traditional Conforming RunLength (CRL) t chart,especially for smaller mean shifts.

Key words: statistical process control, t control chart, average run length