I have a dataset that includes one independent variable with 3 levels (group 1, group 2, and group 3) and a repeated dependant variable (pre test score, post test score).
I am using the statistics package SPSS and when I took the method I thought I would use "repeated measures anova" there didn't seem to be a way of splitting the independent variable into the 3 groups. In the data view of the spreadsheet each row represents a participant and so they are grouped by including a numerical value to each group 1 = group 1, 2 = group 2, and 3 = group 3.
I need to compare the mean changes/improvements over the 2 time points (pre, and post) across the groups to assess if there is a significant improvement in any of the groups.
Do you know the most appropriate approach to do this?
The only option I am considering is creating a new spreadsheet where each row represents a participant and each column represents the difference between pre and post trials, and then entering this into a one way independent anova.
Best Answer
This problem seems the classical repeated measures anova problem, assuming ANOVA hyphothesis to hold. Have you tried to have a glance to the repeated measures ANOVA tutorial ("Show me") in the SPSS help?