You should always look at your design matrix. You can do this through
SPM's review feature OR through MATLAB with the following code:
load SPM.mat
imagesc(SPM.xX.X)
This will show you the columns of the design matrix. Then you will be
able to tell what each column is in the matrix.
You could also look at SPM.xX.name to get the names of each column,
which also should help with the contrast order.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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On Tue, Jul 30, 2013 at 11:37 AM, Glenn Holland
<[log in to unmask]> wrote:
> Hi Christine,
>
>
>
> Thanks for your response. I had read some information that suggested that
> the columns are reversed for the multiple regression design and therefore 1
> 0 would be positive however I don’t know how to confirm this.
>
>
>
> Thanks
>
>
>
> Glenn
>
>
>
> From: Macare, Christine [mailto:[log in to unmask]]
> Sent: 30 July 2013 16:19
> To: Glenn Holland; [log in to unmask]
> Subject: RE: Contrasts for SPM 8 multiple regression
>
>
>
> Hi Glenn,
>
> For a T-contrast you should enter:
>
> 0 1 positive
> 0 -1 negative
>
> Not sure if there is a difference between fMRI and PET in terms of model
> specification though, I had entered these for fMRI analyses.
>
> Hope it helps,
>
> Christine
>
> ________________________________
>
> From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of
> Glenn Holland [[log in to unmask]]
> Sent: 30 July 2013 16:56
> To: [log in to unmask]
> Subject: [SPM] Contrasts for SPM 8 multiple regression
>
> Hi,
>
>
>
> I have a set of 22 PET scan results for a single group and would like use
> SPM to show either a positive or negative correlation with a covariate
> (age). I was going to use the multiple regression option and enter age as
> the covariate but I am unsure how to set the contrasts for this?
>
>
>
> Thanks
>
>
>
> Glenn
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