A Control Chart for Monitoring the Process Mean Using Successive Sampling Over Two Occasions

This article proposes a new control chart to monitor the process mean based on the sample statistics from two successive occasions. First occasion units are independently drawn to obtain information of the study variable, and the second occasion units are drawn collectively with a retained portion of first occasion as matched units, while the other portion is the collection of the fresh units from the remaining unselected units at first occasion. The in-control and out-of-control average run lengths (ARLs) are derived for performance assessment under mean shifts. The performance of the proposed control chart is compared with traditional Shewhart control chart and a EWMA chart in terms of ARLs, which exhibits better performance when process is shifted from the target mean.