On 18 Mar 2009, at 16:54, Kevin Denny wrote:
> I have 7 subjects and 3 conditions. I have used these intstructions
> to set up a
> Tripled T-Test...
>
> http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#higher
>
> So the EVs looks the same as in the website example above, my question
> concerns setting up Contrasts.
>
> I copied their math in setting up the first 3 contrasts A-B, A-C, B-
> C and
> created 3 other contrasts on my own (B-A, C-A, C-B). Is this correct?
>
> EV1 EV2
> A-B 2 1
> A-C 1 2
> B-C -1 1
> B-A -2 0
> C-A -1 -2
> C-B 1 -1
Not quite: B-A should be [-2 -1 0]
> Do I have the 3 bottom contrasts set up correctly? Additionally I
> would like to
> find out where each of the conditions is greater than both of the
> other. So
> where A is greater than B AND C. I assumed I could use the website's
> math in
> creating these by saying A minus B minus C, etc etc for each
> condition. Here
> is what I have come up with in my model...
>
> EV1 EV2
> A 2 2
> B -2 0
> C 0 -2
>
> Is this correct? If not, how would I go about setting up a contrast
> that finds
> where A, B, and C are each greater than the other 2 conditions.
> Thank you
> very much in advance.
I don't think this is what you mean. Do you mean (A>B) AND (A>C) or
A>(B+C)? I suspect you mean the former in which case you generate two
contrasts A-B and A-C and then take the intersection e.g. via post-
contrast masking in the GUI.
Cheers.
>
> - Kevin Denny
> Duke Brain Imaging & Analysis Center
>
>
>
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