GLM, GLZ, GRM, and PLS - Specifying Effects for the Between Group Design

This topic describes the options available in the Predictor variables, Method, and Effects in between design group boxes in the GLM Between Effects dialog box. Use these options to specify a custom (non-default) design. Note that you must first select the Use custom effects for the between design option button in the GLM Between Effects dialog box for these options to be available.

Effects can be specified in the following manner:

· Select the Categorical and/or Continuous predictor variables in the Predictor variables group box by clicking on them; select multiple variables by holding down the CTRL key while clicking on the respective variables; select a list of consecutive variables by dragging the mouse over the list.

· Click on the desired action in the Method group box.

The specified effects will be listed in the Effects in between design group box. You can further edit the effects in the Effects in between design group box by using the following options:

Predictor variables; Categorical, Continuous

The Predictor variables group box contains the Categorical and/or Continuous predictor variables selected for the current analysis. Select the variables you want to include in the design.

Method

The Method group box contains the available options for including the selected variables as effects in the design. Some options may only be available if the appropriate number and types of variables were chosen in the respective Predictor variables group box. See also the description of the GLM syntax, in particular of the DESIGN keyword for details on how to specify designs in GLM, GRM, GLZ, PLS, GDA, and ANOVA. For a discussion of various designs (e.g., surface, mixtures, nested), see the Types of analyses topic in the Introductory Overview.

Add

Click the Add button to add the main effects for the chosen categorical and continuous predictor to the list of Effects in between design.

Full cross

Click the Full cross button to create the respective interaction term for all selected variables (e.g., Gender*Group*Time). Note that this button is only available if two or more categorical and/or continuous predictor variables are selected.

Hierarc. nest.

Click the Hierarc. nest (Hierarchical nesting) button to display the Nesting for Between-Group Factors dialog; in that dialog, specify the nested structure of the design for the selected variables; see also the description of the DESIGN keyword for additional details. Note that this button is only available if two or more categorical and/or continuous predictor variables are selected.

Full factorial

Click the Full factorial button to create a full factorial design for the selected variables (e.g., Group Gender Time Group*Gender Group*Time Gender*Time Group*Gender*Time). Note that this button is only available if two or more categorical and/or continuous predictor variables are selected.

Surface

Click the Surface button to create a response surface design. If a categorical variable was selected, the design will be blocked (e.g., Block Degrees Degrees*Degrees Time Time*Time Degrees*Time; see also the Experimental Design Overview section for details). Note that the variables involved in the surface design will be flagged with an {S} next to them in the Effects in between design group box. Note that this button is only available if two or more continuous predictor variables are selected; it is not available if more than one categorical predictor (blocking variable) is selected.

Mixture

Click the Mixture button to create a second degree (quadratic) mixture polynomial design for the selected variables (see also the Experimental Design Overview section for details). It is assumed that the selected continuous predictor variables are valid mixture variables (i.e., that they add to a constant); this assumption is not checked by STATISTICA on reading the data. Note that the variables involved in the mixture design will be flagged with an {M} next to them in the Effects in between design group box. Note that this button is only available if two or more continuous predictor variables are selected

Fact. to deg.

Click the Fact. to deg. (Factorial to degree) button to create a factorial design (up to the degree specified in the Degree field) for the selected variables (e.g., Group Gender Time Group*Gender Group*Time Gender*Time). Note that this button is only available if two or more categorical and/or continuous predictor variables are selected.

Poly. to deg.

Click the Poly. to deg. (Polynomial to degree) button to create a polynomial design (up to the degree specified in the Degree field) for the selected variables (e.g., Degrees Time Degrees*Degrees Time*Time). Note that this button is only available if one or more continuous predictor variables are selected and no categorical predictor variable is selected.

Degree

Use the Degree field in conjunction with the Fact. to deg. and Poly.to deg. options; see above.

Effects in between design. The Effects in between design group box shows the effects currently in the design. These effects can further be edited via the following options:

Cross

Click the Cross button to cross two effects currently selected in the Effects in between design group box; e.g., if two effects A and B(C) are currently selected, then Cross will add the term A*B(C) to the effects in the design. If more or fewer than two effects are selected, this button is not available.

Nest

Click the Nest button to nest two effects currently selected in the Effects in between design group box; e.g. if two effects A and B are currently selected, then Nest will (1) add the term B(A) (factor B is nested in factor A) to the effects in the model and (2) remove the B main effect from the effects in the model. If more or fewer than two effects are selected, this button is not available.

Remove

Click the Remove button to remove the selected effects from the Effects in between design group box.

Clear all

Click the Clear all button to remove (clear) all effects from the Effects in between design group box.

Note: Reordering effects. To reorder the effects in the Effects in between design group box, first select them (e.g., click on the effect or list of effects), then move the mouse cursor to the desired location in the list, and when the mouse cursor changes to the insertion bar , click the mouse button to move the selected effects.

See General ANOVA/MANOVA and GLM Notes - Specifying Univariate and Multivariate Between-Groups Designs for additional details.