The only correction is that you are not comparing the correlations.
You are comparing the slopes of the the relationship between signal
and your behavioral score. Correlation is a measure that relates the
strength of the relation, not the slope of the relationship. If you
look up correlation, slope and regression, you will get notes on how
correlation coefficients and the slopes (beta) are related (e.g.
http://www.biology.ed.ac.uk/research/groups/jdeacon/statistics/tress11.html)
Best Regards, Donald McLaren
=================
D.G. McLaren
University of Wisconsin - Madison
Neuroscience Training Program
Office: (608) 520-0586
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On Fri, Aug 6, 2010 at 11:35 AM, Maria Densmore
<[log in to unmask]> wrote:
> Hello SPM
> I am running a multiple regression in SPM8, using 2 groups and 1 score,
> where I would like to find where controls show more positive correlation
> with the score than do patients during a task.
> I have chosen
>
> Under Design
>>multipleRegression
> Scans: 8 control and 8 patient con.img files~task>baseline
> Under Covariates
>>3 covariates:
> group, scoreControls, scorePatients
> vector for group:
> 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1
> vector for scoreControls:
> x x x x x x x x 0 0 0 0 0 0 0 0
> vector for scorePatients:
> 0 0 0 0 0 0 0 0 x x x x x x x x
> x=number value
> correlation of score is greater in controls than patients during task:
> [0 1 -1]
> correlation of score is greater in patients than controls during task:
> [0 -1 1]
> activation during task , controls > patients [1 0 0]
> activation during task, patients >controls [-1 0 0]
>
> Please correct where needed.
> Thanks for your time and attention,
> Maria
>
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