You need to use a paired t-test.
On Thursday, February 17, 2011, HwangArum <[log in to unmask]> wrote:
> We conducted 2x2 within-subject design in fMRI study. Each subjects performed two different kinds of tasks A, B in two different contexts X, Y (e.g., X[A-B]-Y[A-B]).
> Is it allowed to make an “interaction analysis” (e.g., [XA-XB]-[YA-YB]) with two-sample t-test in within-subject design (using spm)?
> For example, put [XA-XB] con image into one group and put [YA-YB] con image into another group. If yes, indepence option should be set as yes(default) or should be changed into no?
> Best regards, Arum Hwang
Best Regards, Donald McLaren
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
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