Dear Ivan,
i've got the same error-message a few days ago. In this case i compared two
different models in one study, a blocked and a event-related design. I my case,
the error message was clear, because, the number of scans were different, so
for the F-Test, the degrees of freedom are different. In the conjunction
analysis
of the F-Test, the degrees of freedom must agree, because you test the
combination
of two parts of the design matrix, with you whole design matrix. So, the result
of the F-Test is defined by the two degrees of freedom. In my case, there was
a third on, so the implemented F-Test can't work.
Is there something similar to your study ?
Karsten
Ivan Toni wrote:
> Dear SPMers,
>
> I am trying to run a conjunction on the effect of a condition across
> different sessions using F contrasts in SPM99b. However, I got the
> following error message:
>
> SPM99b: spm_getSPM (v2.20) 12:01:07 - 01/09/1999
> ----------------------------------------------------------------
> contrast structure : ...saved to xCon.mat
> SPM computation : ...initialising
> ??? Error using ==> spm_getSPM
> illegal conjunction: can only conjoin SPMs of same STAT & df
> Error in ==> /opt/SPM/spm99b/spm_results_ui.m
> On line 238 ==> [SPM,VOL,xX,xCon,xSDM] = spm_getSPM;
> ??? Error while evaluating uicontrol Callback.
>
> The contrasts used are those provided as default by the SPM contrast
> manager and they are relative to the effect of a given event within each
> session of an event-related multi-session study. Am I doing something
> stupid or is there a bug somewhere ?
>
> Thanks in advance,
> Ivan Toni
>
> --
> Ivan Toni Ph.D.
>
> Institut für Medizin
> Forschungszentrum Jülich
> D-52425 Jülich
> Deutschland
>
> tel. 49 2461 61 2483
> fax. 49 2461 61 2820
> email: [log in to unmask]
--
-------------------------------------------------
Dipl. phys. Karsten Specht
Institut fuer Medizin
Forschungszentrum Juelich GmbH
Leo-Brand-Strasse
D-52545 Juelich
Germany
Phone ++49-2461-61-2090
Fax ++49-2461-61-2820
E-Mail [log in to unmask]
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