Defining Variables for X and Moving Range Chart and CUSUM Chart - Quick Tab
Select the Quick tab of the Defining Variables for X and Moving Range Chart dialog box to access the options described here.
Variables
Click the Variables button to display a standard variable selection dialog box. Here, you can select Variables with measurements and Variables with part identifiers (optional for short run charts).
Constant number of samples per part
If this check box is selected and no part identifier variable is selected, you can specify here a fixed number of consecutive samples for each part. For example, if your input data consist of batches with different specifications ( different parts) from which a fixed number of samples is automatically drawn, then you can select this option so that on reading the data each chunk of k consecutive samples is automatically assigned to the same part.