I have a 2x2 flexible factorial design in fMRI and wish to report main effects and the interaction.
When I run the F contrast for Main effect of Group and click whole brain analysis, many voxel clusters appear. So I must follow up with t-tests to understand in which the direction the groups differ. Do I write this as: Group1 had significantly more voxel activation in the (e.g.) amygdala region than Group2 (t(64) = etc. and then report the t and p values?
If there are many voxel clusters, what's the best way to set a minimum threshold?
Lastly, when I run the Group x Condition interaction, no suprathreshold clusters appear - with no F statistic, how do I formally report this?
Many thanks in advance.