Cusum Charts — Give Your Data a New Look Available to Purchase

Cumulative Sum methods were first developed 30 years ago as an alternative to conventional quality control charts. In this article, the basic features of Cusum plotting are introduced, largely through a practical example. Cusum charts, either as an alternative or (preferably) a supplement to conventional “run” charts, assist in identifying instabilities or special causes of variation — an important aspect of process control and improvement. Location of change points and estimation of local averages (valuable in diagnosis of causes and calculation of corrections required to restore target conditions) are particular advantages of Cusum methods.