Hello,
I am attempting to analyze a 3x3 within subjects ANOVA using SPM5.
Using the flexible factorial setup, I created three factors
1. subject
2. cond1
3. cond2
and then set up the subjects to have 9 images each (to complete the 3X3).
Then, in the main effects & interactions section, I set up the three main
effects, and the interaction between cond1 and cond2 {[2 3]}.
Design1:
When I estimate this, I can not generate any valid contrasts (e.g., 2 -1 -1;
0 1 -1 is not valid).
Design2:
If I drop the interaction, I can get the main effects.
Design3:
If I drop the main effects, I can estimate other contrasts (e.g., [2 2 2 -1
-1 -1 -1 -1 -1; 0 0 0 1 1 1 -1 -1 -1]) for the first main effect.
I am a little confused about how I should be running this. I would think
that Design1 above is the way that I should do this, but is it perhaps
Design3 -- and then I set up the main effects in the contrast editor?
Any help would be greatly appreciated.
Thanks in advance,
Wil
|