Specify historical parameters for Normal Capability Analysis for Multiple Variables

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.

Historical means

Specify the mean of the population distribution for each variable.

Historical Standard Deviations

Within subgroups

Specify the within-subgroup standard deviation of the population distribution for each variable.

Between subgroups

Specify the between-subgroup standard deviation of the population distribution for each variable.

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.