Hi Steve-
Thanks for your help.
I just want to confirm one thing though...
I understand with the way you set up the EVs, but to compare groupA
vs groupB ML-MH for condition C, shouldn't the contrast be [1 -1 -1 1]?
and not [1 0 -1 0] as you wrote.
My understanding is that would be a comparison of groupA cope1 vs
groupB cope1, right?
Thanks again.
R
On Jun 17, 2007, at 6:08 PM, Steve Smith wrote:
> 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
>
>
> ----------------------------------------------------------------------
> -----
> 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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