New Sensitizing Runs Rules for Shewhart type Control Charts with Applications

Abstract: The most popular tool used in the industry for monitoring a process is the Shewhart control chart. The major disadvantage of the Shewhart control chart is that it is not very efficient in detecting small process average shifts. To increase the sensitivity of Shewhart control charts to small shifts additional supplementary runs rules has been suggested. In this paper we introduce and study the modified r/m control chart which has an improved sensitivity to small and moderate process average shifts as compared with the standard Shewhart X-bar control chart and corresponding control charts proposed recently in the literature.