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. The ...

The control chart basics.2 types of variation and how we distinguish between common and special cause variation, along with how to create a rational subgroup. We also cover the equations and constants ...

To calculate the x-bar or sample mean, you would sum all the data points in the sample and then divide by the number of data points. This will be represented by the following formula: ...