Remove the group covariate. This will solve your problem. The issue is
that you had two columns that were identical in your design matrix.
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, Oct 30, 2012 at 6:50 AM, Gabriel Go.Es. <[log in to unmask]> wrote:
>
> Dear SPMers
>
>
> I'm having trouble when trying to set some constrasts for my statistical
> design (see atteched image)
> group was entered as a categorical variable with 1's and -1's and gender as
> 1 & 2's
>
> My problem is that, when I make the same design but without the group
> variable, everything works perfectly, but when I do introduce the group in
> the model
> I always get the following error:
>
> 1 -1 0 0 0 0 0 <- !invalid contrast
> Failed 'Contrast Manager'
> Error using ==> spm_run_con at 228
> Error in contrast specification
> In file "C:\Program Files\MATLAB\R2009b\work\spm8\config\spm_run_con.m"
> (v3993), function "spm_run_con" at line 228.
>
>
>
> The only valid contrast is possible when I do set the ANCOVA option to YES,
> is when thesting the columns of globals@ as:
> 0 0 0 0 0 1 -1
> but not sure what I'm testing on such contrasts.
>
> How can I test my group differences with my initial model? by accounting for
> the effect of all my variables. Is it real possible? or I do have to somehow
> change to fix my model.
>
>
> Many thanks in advanced,
> Gabriel
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