Two Alternatives to the Shewhart X̄ Control Chart

Abstract

Average run length (ARL) values are calculated for two X̄ control chart schemes and compared with those of a standard Shewhart chart. Both control charts are based on runs rules and are easily implemented. An out-of-control condition for one of the charts is a run of two of two successive points beyond a special control limit. The other chart uses a run of two of three successive points beyond a different control limit. Both schemes are shown to have better, that is, lower, ARL values than the standard Shewhart chart for process average shifts as large as 2.6 standard deviations from the mean.

• Average Run Length
• Control Charts
• Runs Test

Additional information

Notes on contributors

Morton Klein

Dr. Klein is a Professor in the Department of Industrial Engineering and Operations Research. He is a Member of ASQ. His email address is [email protected].