Use S Chart to monitor the variation (standard deviation) of your process when you have continuous data and subgroups sizes of 9 or more. Use this control chart to monitor process stability over time so that you can identify and correct instabilities in a process.
For example, a paint manufacturer wants to determine whether the filling process for cans of paints is stable. Operators collect subgroups of 10 cans every hour for 30 hours and use an S chart to monitor the variation of the filled paint cans.
Where to find this control chart
To create an S chart, choose Stat > Control Charts > Variables Charts for Subgroups > S.
When to use an alternate control chart
For subgroups that have 2−8 observations, use R Chart.