Specifications for Capability Analysis

Click the Process capability button on the Specs tab of the Results dialog box to display the Specifications for Capability Analysis dialog box.

Nominal ± delta

This is the default setting. You can leave the values in the Nominal field and the ± delta field displayed below the Type option at their defaults, or you can enter the nominal target specification and the deviation (delta) defining the specification range.

Lower, nominal, upper

When this type is selected, the Nominal field, Lower specification limit (LSL) field, and Upper specification limit (USL) field are displayed below the Type option. In this setting, you can define a specification range that is asymmetrical about the design center (nominal target).

Lower, Nominal. When this type is selected, the Nominal field and Lower specification limit (LSL) field are displayed below the Type option. In this setting, you can set one-sided specification limits.

Nominal, Upper

When this type is selected, the Nominal field and Upper specification limit (USL) field are displayed below the Type option. In this setting, you can set one-sided specification limits.

Process capability sigma limit

The value entered here will determine the process range that is shown in the summary histogram and that is used for the computation of the process (machine) capability indices. In short, this value will determine what is considered the practical range of values produced by the process. The default setting (± 3 times sigma), is the commonly recommended value.

OK (compute)

Click this button to close the dialog box and display a spreadsheet of the computed capability indices.

Close (set specs)

When you click this button, the dialog box closes and the current specifications will be set and "remembered" when you subsequently produce a control chart (and select to compute and display the process capability indices in the chart).

Cancel

Click this button to close the dialog box without saving any changes.