Repeated Measures of ANOVA

• Used when the research involves changes in mean scores over three or more time points, or when differences in mean scores under three or more different conditions/groups.
• Method:
  • Analyze
  • General Linear Model
  • Repeated Measures
  • Rename within subject factor name with IV
  • Add number of groups in the number of levels section
  • Add DV in the measure name section
  • Click on Define
  • Move the relevant groups to the section under within-subject variables
  • Plots

• Move the IV to the horizontal axis
• Click continue
• Options
• Move IV
• Click on descriptive stats and estimates of effect size
• Click compare main effects and select Bonferroni

Output:

• If Mauchy’s test for sphericity is significant, it means that the assumption of sphericity has been violated and score from Greenhouse-Geisser can be checked
• If the scores on Greenhouse-Geisser are significant, then the differences in the 3 levels of the IV are significant.
• If you look at the table of pairwise comparisons you can see the differences between any two groups of the 3 tested. If they are significant you can conclude that two groups differed significantly from one another at a certain level