Why wouldn't you want to demean? See Jeanette Mumford's web page on
this.
Also, you need to include an intercept term in your model. See
http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#SingleGroupAveragewithAdditionalCovariate
as an example.
cheers,
-MH
On Wed, 2011-11-16 at 20:08 +0000, Rodrigo Perea wrote:
> I think I understand what to do but if somebody could confirm that what I do is correct, it will be great.
>
> I want to create a design matrix lets where I use Var3 as a regressor with sex and age as a covariates in a group of individuals. I would do it without demeaning the age...is this correct?
>
> Lets say I have 5 subjects, my design.mat will look like:
> Sex Age Var3
> 1 75 1634.75
> 0 75 1153.25
> 1 83 3151
> 0 73 1651
> 0 81 1503.25
>
>
>
> and my design.con would look like:
>
> 0 0 1
> 0 0 -1
>
> Thanks in advance,
> Rodrigo
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