In some cases,the xbar-chart is used without an R-chart because there is no variation between the samples.

Question

Quizplus · Accepted Answer

The R-chart is used to monitor the variability between the subgroup samples. If there is no variation between the samples, it means that the process is stable and in control, and hence it would be appropriate to use only the xbar-chart. However, it is uncommon for there to be absolutely no variation between the samples.

In Some Cases,the Xbar-Chart Is Used Without an R-Chart Because