Specify Contrasts for this Factor / Enter Contrasts for this Factor / Contrasts for Dependent Variables

This dialog box may be named Specify Contrasts for this Factor, Enter Contrasts for this Factor, or Contrasts for Dependent Variables, depending on the way in which it was displayed. Select one effect in the Effect drop-down box and click the Contrasts for LS means button on the GLM, GRM, or ANOVA Results dialog box - Comps tab (or the Specify contrasts for LS means button on the GLM, GRM, or ANOVA More Results dialog box - Planned Comps tab) to display the Specify Contrasts for this Factor dialog box. Note that the Specify Contrasts for this Factor dialog box will also be displayed when you select an interaction in the Effect drop-down box that includes two or more between effects and one within-subjects (repeated measures) effect (or two or more within-subjects effects and one between effect). If this is the case, the Specify Contrasts for this Factor dialog box will be displayed after you click the OK button in the contrast specification dialog box that was used to first specify the contrast coefficients for the two or more between effects (or within-subjects effects).

Click a factor name button in the Specify Contrasts or the Repeated Measures Factors dialog box to display the Enter Contrasts for this Factor dialog box. Finally, select the Yes option button in the Contrasts for dependent variables group box, and then after you have specified the contrast coefficients for the selected Effect, click the OK button in the various contrast specification dialog boxes to display the Contrasts for Dependent Variables dialog box.

CONTRASTS. Specify the contrast coefficients for the selected factor/dependent variable in the CONTRASTS specification column(s). To learn more about the logic and interpretation of contrast analysis refer to the ANOVA/MANOVA module Overview; examples of how to specify contrasts are also discussed in that module, in the Notes, for between-group designs as well as repeated measures designs.

The general rules for generating contrast coefficients are as follows:

(1) The contrast must have as many coefficients as there are levels for the respective factor.

(2) Levels that are to be omitted in the contrast are assigned a 0 (zero).

(3) Levels that are to be compared against each other are assigned positive or negative integer values; however, it is important that the sum of such contrasts is equal to zero.

(4) Levels that are to be collapsed are assigned identical integer values (e.g., all 1's).

If the highlighted factor has more than two levels, then several pre-defined sets of contrasts are also available, including contrast coefficients for testing orthogonal polynomials (trend analysis).

OK. Click the OK button to close the dialog box and return to the GLM, GRM, or ANOVA Results dialog box - Comps tab, after you are satisfied with the current contrast coefficients.

Cancel. Click the Cancel button to close the dialog box and return to the GLM, GRM, or ANOVA Results dialog box - Comps tab, disregarding any changes made.

Delete column. Click the Delete column button to delete the entire selected column.

Quick Fill (Insert Value). The Quick Fill (Insert Value) group box allows you to quickly enter contrast coefficients. Select the Cell option button and click one of the number buttons to replace the coefficient in the cell for the selected variable with that number (i.e., only that cell will be replaced). Select the Row option button and click one of the number buttons to replace all of the coefficients for a variable with the selected number (i.e., the entire row of contrast coefficients will be replaced with this number). Finally, select the Column option button and click one of the number buttons to replace the coefficients for all of the variables with the selected number (i.e., the entire column of contrast coefficients will be replaced with this number). Note that these option buttons will only be available when applicable.

Predefined. Use the options in the Predefined group box to access other dialogs that allow you to further specify the contrast coefficients. Click the Polynomial button to display the Polynomial Coefficients dialog box. Click the Other button to display the Predefined Contrasts dialog box. Note that this group box is only available in the Contrasts for Dependent Variables dialog box when there are three or more dependent variables in your design.

<<. Click the << button to display the previous CONTRASTS column. Note that this option will only be available when applicable.

>>. Click the >> button to display the next CONTRASTS column. Note that this option will only be available when applicable.

See also GLM - Index.