Hi,
On 15 Jun 2007, at 17:14, Remya Nair wrote:
> hi-
>
> i was hoping someone could help me set up an anova.
>
> let me describe the experiment:
>
> there are 2 groups with 12 subjects in each group.
> each subject did 8 runs (4 run for condition C and 4 runs for
> condition P, with 3 levels for each condition (ML/MH/SH)).
>
> i ran the first-level analysis with 3EVs (ML/MH/SH) and then combined
> the 4 runs of a single condition.
>
> now i have 2 .gfeat directories for each subject: 1 for condition C
> and one for condition P (each has 4 cope.feat dirs - ML, MH, SH,
> MH-SH).
>
> i want to look at the group differences across different conditions
> e.g., groupA vs groupB, looking at ML-MH for condition C.
>
> so i would have 48 inputs in my higher level analysis:
> 12 groupA cope1
> 12 groupA cope2
> 12 groupB cope1
> 12 groupB cope2
>
> but i am not sure how to set up my EVs and contrasts.
Something like:
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 1 0 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
and for the question:
> e.g., groupA vs groupB, looking at ML-MH for condition C.
use the contrast [ 1 0 -1 0] etc.
> also, what if i want to look at ML vs. (MH-SH)?
Probably the best thing is to achieve this contrast at first-level
making the higher-level analyses easy. At first level this would be:
[1 -1 1] though I'm not sure whether you do exactly mean ML - (MH-SH)
> likewise, is it possible to look at group differences across
> conditions C+P?
Sure - in a similar manner to the above.
Cheers, Steve.
>
> thank you in advance!
>
> R
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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