I'm sorry if my post was a little confusing.
I guess my main concern is that I'm not seeing the complete picture of
activation in my contrast.
I'm basically running a paired 2 sample t-test with 10 subjects.
I used the same setup in the example in the FSL "Paired Two-Group
Difference (Two-Sample Paired T-Test)" example.
When I run my contrast A-B:
So here are my issues:
(1) I see activation only at the A-B level, but not at the B-A level.
Is this normal? Something seems strange about this?
(2) What does A-B actually mean?
I was assuming that "A-B" indicates significant difference in any direction
(postive or negative)? If so, then what would be the need for B-A contrast?
(3) Does A-B mean only A>B, i.e. activation reflecting areas in the brain
where A is significantly greater/larger than B?
And, thus, if B is significantly larger than A, then it won't show up in
the contrast map of A-B.
Your help greatly be appreciated.
Thanks
Mike
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