Dear FSL users & experts,
I have 20 subjects, who were split into two intervention groups (n=8 drug, n=12 placebo), and underwent a task fMRI at two time points (pre and post intervention).
I was hoping to test for whether there is a:
- a main effect of intervention (the between subject factor)
- a main effect of time (the within subject factor)
- an interaction between the two factors
I thought that the 2-way mixed effect ANOVA might be the way to do it (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#ANOVA:_2-groups.2C_2-levels_per_subject_.282-way_Mixed_Effect_ANOVA.29) but am a little confused as to how exactly to set it up.
In the example given:
- does 'run' signify a factor with different levels or two runs done to acquire more data?
- if the former, am I right in thinking that C1 (run effect) would give me the effect of the within subject factor?
- am I right in thinking that C2 would give me the effect of the interaction between of the two factors? i.e. there is no contrast which would give me the effect of the between subjects factor?
Many thanks in advance for your help!