Dear Ivan,
> 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 ?
This is interesting. I suspect that you are doing a conjunction of
F-contrasts but the effective degrees of freedom are not identical.
They will be for T contrasts because this is the d.f. due to error
(which will be the same for all sessions). However the d.f. for the F
ratio numerator is a function of the interesting parition of the design
matrix.. If these are in any way different then the d.f.s will differ
and the routine will pick this up.
I will look into this but in the imterim use T-Contrasts.
With very best wishes - Karl
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|