Dear Simon,
Sorry for bother You again, but I have got one more thong to clarify:
Do You mean conjuction, like:
contrast [1 -1 0] masked (exclusively) with contrast [1 0 -1]?
Thank you for your help,
Tibor
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On
Behalf Of Simon B. Eickhoff
Sent: Friday, January 05, 2007 2:02 PM
To: [log in to unmask]
Subject: Re: [SPM] Three Conditions, A > B & C
Dear Tibor
Your approach sounds reasonable, although you might want to consider unequal
variances between conditions to have a full model of non-sphericity.
Regarding your contrast question, the choosen contrast depends on your exact
hypothesis/question
If you want to identify those regions, where the BOLD response to condition
A is larger than the AVERAGE of conditions B and C, you have to enter [2
-1 -1]
If you want to identify those regions, where the BOLD response to condition
A is larger than the SUM of conditions B and C, you have to enter [1 -1
-1]
If you want to identify those regions, where the BOLD response to condition
A is larger than that in condition B AND larger than that in condition C,
you have to perform a conjunction analysis between [1 -1 0] and [1 0 -1]
Hope this helps
Simon
> -----Original Message-----
> From: SPM (Statistical Parametric Mapping)
> [mailto:[log in to unmask]] On Behalf Of Auer, Tibor MD.
> Sent: 03 January 2007 19:36
> To: [log in to unmask]
> Subject: [SPM] Three Conditions, A > B & C
>
>
>
> Dear SPMers,
>
>
>
> At first I would like to wish a Happy New Year for all!
>
>
>
> I need a help in setting design and contrast to examine the
> positive effect of conditionA relatively to conditionB and C.
>
>
>
> I have created the first-level contrast for all the subjects and
> conditions:
> condA > rest,
>
> condB > rest,
>
> condC > rest,
>
> all per 10 subjects.
>
>
>
> In the next step, I have set up a second-level analysis as a one-
> way ANOVA with one factor and three levels:
>
> Name: conditions
>
> Level: 3 (A, B, C)
>
> Independence: No (same subjects)
>
> Variance: equal
>
> and with three cells:
>
> 1: 10 con*.imgs for condA
>
> Factors: 1
>
> 2: 10 con*.imgs for condB
>
> Factors: 2
>
> 3: 10 con*.imgs for condC
>
> Factors: 3
>
>
>
>
>
>
>
> To define contrast I used t-contrast, using [2 -1 -1].
>
>
>
> Does it work for my purpose?
>
>
>
> Please Help!
>
>
>
> With many thanks and Best Wishes,
>
>
>
> Auer, Tibor MD.
>
> PhD-student
>
> Pécs University, Faculty of Medicine
>
> Neurosurgery Clinic
>
> [log in to unmask]
>
> +36-20-986-9341
>
>
>
>
>
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-----------------------------------------
Simon Eickhoff
Institut for Medicine (IME); Research Center Jülich
Leo-Brandt-Str. 5; 52425 Juelich, Germany
Phone + 49 2461-61-5219 / Fax + 49 2461-61-2820
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