Characteristics of Shewhart Charts . Figure 1 illustrates a typical Shewhart chart.. Figure 1: A Shewhart Control Chart All Shewhart charts have the following characteristics: Each point represents a ...

Key Points X-bar and R charts are useful control charts for use with rational subgroups. X-bar measure between-sample variation. R charts measure within-sample variation. All processes vary.

Part 1 of this article series demonstrates, using real-world process data, that the four fundamental assumptions underlying the classical Shewhart control charts—randomness, independence, constant ...