Process Capability Analysis Setup--Raw Data - Grouping Tab

Select the Grouping tab of the Process Capability Analysis Setup - Raw Data dialog box to access the options described here.

Variables

Click the Variables button to display the standard variable selection dialog box, in which you select the variables with the process measurements of interest, and an optional grouping variable with codes to identify to which sample each observation belongs.

If a grouping variable is specified, Statistica will compute capability indices (based on the inherent variation) and performance indices (based on the total variation; see ASQC/AIAG, 1991).

Process specs

Click the Process specs button to display the Enter/edit specification limits dialog box, in which you specify the process (engineering) specification limits from which the capability indices (such as Cpk) and performance indices (such as Ppk) will be calculated.

Grouping (process capability/performance)

The Grouping (process capability/performance) group box contains the options described here:

No grouping (single sample)

Select the No grouping (single sample) option button (the default setting) when you have not selected a grouping variable (see Variables above).

Constant sample size

Select the Constant sample size option button and enter a constant sample size number in the adjacent box (or use the microscrolls) if you do not have a grouping variable but a consistent number of samples for each observation.

Grouping variable

The Grouping variable option button is only available if you have specified a grouping variable.

Select this option button when you have selected a grouping variable (see Variables above). The variable you selected as your grouping variable is displayed in the adjacent field.

Select all codes

Select the Select all codes check box if you want Statistica to use all of the codes in your grouping variable for your analysis.

Codes

This option is only available if a grouping variable was specified (see Variables above). Click the Codes button to select the codes that were used in the grouping variable to identify to which sample (group) each observations belongs.

 Statistica will use only the codes that you specify here for your analysis. For more detailed information see Select codes for.

Keep codes in data file order

Select the Keep codes in data file order check box if you wantStatistica to keep the codes in the order that they were entered in the data file.

Estimate sigma from

The Estimate sigma from group box contains three option buttons.

Select the appropriate option button to specify if you want to estimate Sigma from either the Ranges, Standard deviations, or Variances of the values in each group.

The Estimate sigma from group box is only available if you selected a grouping variable.