Memorandum 1569

Are estimated control charts in control?

W. Albers & W.C.M. Kallenberg

Abstract:
Standard control chart practice assumes normality and uses estimated parameters. Because of the extreme quantiles involved, large relative errors result. Here simple corrections are derived to bring such estimated charts under control. As a criterion, suitable exceedance probabilities are used.

Keywords:   Statistical process control, Shewhart, exceedance probability, tolerance region

Mathematics Subject Classification:   62F25, 62P30