This message usually occurs, if you have specified unestimable covariance
components. You can review the specified components with "Review
design|Explore Covariance structure". Most probably, there are too many
components. Try to restrict your assumptions about unequal
variances/dependent errors to the absolutely necessary factors.
On Thu, 26 Jan 2006, Kris Knutson wrote:
> During a multiple regression of PET data, estimation step, I repeatedly get the same error:
>
> Temporal non-sphericity (over voxels)... REML estimation.
> Warning: Matrix is singular to working precision.
> In spm_remL at 87
> spm_spm at 860
> spm_spm at 299
> ??? Error using ==> svd
> Nan or Inf prevents convergence
> Error in ==> pinv @ 29
>
> The error occurs even though the same PET scans work fine in a one sample t-test.
>
> Any help pointing to the source of the error would be greatly appreciated.
>
> Also, for the multiple regression (PET) option, why are they two different places to enough
> covariates? What is the difference?
>
> Thanks.
>
>
--
Volkmar Glauche
-
Department of Neurology [log in to unmask]
Universitaetsklinikum Freiburg Phone 49(0)761-270-5331
Breisacher Str. 64 Fax 49(0)761-270-5416
79106 Freiburg
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