Dear, SPMers
I'm new in SPM and it's giving me a hard time.
Currently I'm trying to do a 2-way repeated measure ANOVA in MRI study:
two groups (experimental and control) and two time points (baseline and
follow-up).
I wanted to look at main effects for group and time, and an interaction
effect between group and time.
So I entered groups in this order: E1 E2 C1 C2.
Contrasts that I entered for group, time and interaction were 1 1 -1 -1,
1 -1 1 -1 and 1 -1 -1 1 respectively.
Time and interaction contrasts seemed okay but the group contrast of 1 1 -1
-1 indicated "invalid contrast".
I couldn't figure out what went wrong in this design? (I used VBM2_
longitudinal data analysis toolbox designed by Christian Gaser)
Can anybody help me and give me a tip on this problem?
Ji-Youn Yi
Research Assistant
Department of Neuroscience
Seoul National University, South Korea
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