2-Way Analysis of Variance (ANOVA):
Some SPSS screenshots

H. Bruce Lammers, Ph.D.
Marketing Research Technology Center
California State University, Northridge

The examples below assume an experiment on the effects of color (red vs blue) and packaging (round vs rectangular) on purchase intention.

Main effect stands for the "effect of one independent variable alone on the dependent variable." The usual wording of a main effect goes something like this: "The main effect of color on purchase intention was (not) significant."

Interaction effect stands for the "combined effect of two or more indendent variables on the dependent variable." The usual wording of an interaction effect goes something like this: "The interaction of color and shape on purchase intention was (not) significant."

To run the 2-way ANOVA:
 

To Get to ANOVA in SPSS.
Select your Independent Variables (factors) and your Dependent Variable.
Selections to make on the MODEL button.
Selections to make on the CONTRASTS button (none).
Selections to make on the PLOTS button (none).
Selections to make on the POST HOC TESTS button (none).
Selections to make on the SAVE button (none).
Selections to make on the OPTIONS button (important).
Results: Main Effect of Color on Purchase Intention.
Results: Main Effect of Shape on Purchase Intention.
Results: Interaction Effect of Color x Shape on Purchase Intention.
Results: Interaction Means for the Significant Interaction Effect.

Graphing the Significant Effects
To Get To Bar Graphing in SPSS.
Select Clustered Bar Graphing.
 Example Setup for Graphing a Significant ANOVA Interaction.
Results: Graph of Significant Color x Shape Interaction on Purchase Intention