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Dear SPM'ers,

I would very much appreciate your insight on the best way to perform a group analysis in the following situation (SPM2):
I have 2 groups of subjects (group A receiving ttt x, group B receiving a placebo) and 1 control group C.
Groups A an B have been scanned at baseline and after ttt/placebo. Control group has been scanned once. All subjects performed the same test.
I would like to know 
1)whether there is a difference between groups A and B after ttt
and 2) whether there is a difference between the control group and groups A and B before and after ttt/placebo

For the 1st question I was going to perform a paired t-test analysis (A1vsA2; B1vsB2) since both groups have been scanned twice followed by a 2 sample t-test on the resulting con.images (A.con vs B.con). Would that be correct?

For the second question would it be correct to perform a one-way ANOVA specifying 5 groups (A1 A2 B1 B2 and C)? 

Finally, what is the difference between one way ANOVA and one way ANOVA with constant?

Any help will be very much appreciated.

Thank you very much!

Olga