Dear SnPMers,
We have a block multisubject fMRI study with a 2 factor x 2 level
design (4 conditions).
At the first level I obtained t-contrasts for 2 main effects and
interactions, like
1 1 -1 -1 (main effect 1),
1 -1 1 -1 (main effect 2),
and, e.g. 1 -1 -1 1 (interaction effect)
Now I want to perform F tests on those effects at the second level.
In case of SPM, I just take corresponding con-images, run the
one-sample t-test and then look at the F (effect of interest) contrast.
I hope, that's a correct way to do.
However, I would like to perform the same F tests for the main effects
and interaction with *SnPM*, and here I've
got stuck, because SnPM always splits an effect into a negative and a
positive part.
Should I, e.g., create some other contrasts at the first level to
enter those into withing-subject ANOVA in SnPM?
Could someone please give me a helping hand?
PS: I use SPM 2 and SnPM 3
best regards,
Victor
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