An expected cost model for the fraction defective control chart for the case where there are several out-of-control states is developed. A procedure is presented for determining the sample size, control limit or critical region, and interval between samples which minimizes the expected cost of...

Erratum To "Economic Design of Fraction Defective Control Charts" By Montgomery, Heikes and Mance, Management Sci. 21 (11, July) (1975).

We provide an introductory overview of the Six Sigma development and improvement processes. A historical perspective is provided. We also discuss the statistical methods frequently used within this framework and briefly comment on the impact of Six Sigma on the practice of statistics in...