In Statistica, go to "File" |" Open Examples" to browse and load Statistica example data "CreditRisk.sta" for illustration purpose (CreditRisk.sta usually locates at "C:\Program Files\Dell or StatSoft\Statistica 13\Examples\Datasets\")

ANCOVA (Analysis of covariance) can be performed within "General Linear" (GLM) or "Generalized Linear/Nonlinear" (GLZ) or "General Regression" (GRM) modules in Statistica.

Go to "Statistics" | "Advanced Models" | "General Linear" or "Generalized Linear/Nonlinear" or "General Regression" module.

Resolution 1: 

1. In the GLM or GLZ or GRM module dialog, Choose "Analysis of covariance" as "Type of analysis" and "Quick specs dialog" as Specification method. Click OK.

2. In the "Analysis of covariance" dialog, click on "Variables" tab to specify dependent (continuous), independent (categorical), and cofactors (continuous) variables. 

Click Ok.

3. In the "General custom design" dialog, find the "Between effects" tab.

In the case that the "Between effects" tab is inactive (greyed out) as in below figure, Click on OK to first get to the analysis result dialog. 

In the result dialog, click on "Modify" button which will direct you back to "General custom design" specification dialog with "Between effects" tab active.

4. Click on the "Between effects" tab to specify the main effects, co-effects and interactions terms. 

Click OK.

5. The ANCOVA result dialog with main effect, co-factor effect and interaction terms in the model. 

Resolution 2:

1. In the GLM or GLZ or GRM module dialog, Choose "Analysis Wizard" as Specification method. Click OK.

2. A dialog will pop out asking user to choose dependent, independent and covariates.

Click Ok.

3. In the "Analysis Wizard -- Between Design" dialog, find the "Custom between design" tab.

4. Click on the "Custom between design" tab to specify the main and cofactor effects and interaction terms. 

Click "OK(Run)".

5. The result dialog: