Cumulative Sum Control Charts and the Weibull Distribution

A method for construction of cumulative sum control charts for controlling the mean of a Weibull distribution is described. As a special case, charts appropriate to exponentially distributed variables can be constructed. There is some investigation of the results of using such charts when a non-exponential Weibull distribution would be more appropriate. The paper concludes with a discussion of certain formulas in the related analysis of sequential probability ratio tests for Weibull distributions.