Dear SPMers,
I have a few question about running repeated measurement ANOVA in SPM8. In my study design, I have two group and one within-subject factor with two group, i.e. each participants have two condition.
I did the following to set up the GLM.
1st factor:
Name: subject
Independence: yes
Variance:equal
2nd factor:
Name: group
Independence: yes
Variance: unequal
3rd factor:
Name: condition
Independence: no
Variance:equal
(This is a within-subject factor)
I would compute the main effect and the interaction between #2 and #3
Then I get a design matrix ( group1, group2, condition1, condition2, group1condition1, group1condition2, group2condition1, group2condition2)
I set up following contrast to test the effect
Main effect of group : 1 -1 0 0 .5 .5 -.5 -.5
Main effect of condition : 0 0 1 -1 .5 -.5 .5 -.5
Interaction : 0 0 0 0 1 -1 -1 1
I have a question that what is the meaning of the result from main effect of group/ condition? And the result from interaction?
Best regards,
Yvonne
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