You can choose to have Minitab use historical population parameters to evaluate process capability. Historical parameters can be based on estimates from past data.
For each parameter, you can enter one value, multiple values, or a column. If you enter one value, it applies to all variables or groups. If you enter multiple values or a column of values, the values correspond sequentially to the columns that you entered in Variables or to the groups in the By variables column.
If you do not enter historical parameters, Minitab estimates the mean and standard deviations from your sample data and uses those estimates to calculate process capability.
If you want to specify the method that Minitab uses to estimate the standard deviation from your sample data, click Estimate.