Process Capability Analysis Setup--Aggregated Data - Advanced Tab

Select the Advanced tab of the

Process Capability Analysis Setup--Aggregated Data

dialog box to access the options described here.

Variables

Click the Variables button to select

1. A variable containing the sample means.
2. A variable containing the index of within-sample variability (such as, range, standard deviation, or variance).
3. A variable containing the sample sizes.

Measure of variability (contained in the second variable)

The Measure of variability (contained in the second variable) group box contains three options: Ranges, Standard Deviations, and Variances. The option selected here determines whether Statistica expects ranges, standard deviations, or variances in the second variable selected (see Variables above).

Ranges

When Ranges is selected, the within-sample Sigma is estimated as R-bar/d2 (see, for example, Montgomery, 1985, 1991; see also Quality Control)

Standard Deviations

When Standard Deviations is selected, Statistica computes the within-sample Sigma as S-bar/c4 (see, for example, Montgomery, 1985, 1991).

Variances

When Variances is selected, Statistica will compute the square root of the average within-sample variance.

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 to be used in the computation of the capability (such as Cpk) and performance (such as Ppk) indices.