Improving the efficiency of various Shewhart control charts

We modify various Shewhart charts such as the np control chart, X-bar control, and S-2 control chart using modified multiple dependent state sampling. The efficiency of the three charts is evaluated in terms of the average run lengths. The operational procedure of the proposed charts is discussed using simulation and factory data. We showed the efficiency of the proposed control chart over the existing control charts in terms of average run length. The results show that the proposed control charts are more effective to detect a smaller shift in the process than existing Shewhart charts.