Dear Hector,
In your example, you are setting up a model with 13 data points (images)
and 13 regressors. The last regressor is redundant so you actually have
one degree of freedom left. The error message is not the clearest but
statistical inference is going to be challenging here...
Best regards,
Guillaume.
On 20/04/17 18:35, Hector Espinos wrote:
> I'm doing the second level analysis in SPM software.
> I do the differences between groups. I have three groups (control,
> patients with EHM and patients without EHM).
> Now I have done a multiple regression with covariates for each group.
> The covariates (9 covariates in total) are biochemistry parameters and
> oxidate/nitrosative biomarkers.
> I have done without problems the multiple regressions for the control
> group and for the patients with EHM group.
> Hovewer when I do the same with the other group (patients without
> EHM)appear the follow error:
>
>
>
>
> SPM12: spm_results_ui (v6200) 19:20:31 - 20/04/2017
> ========================================================================
> SPM computation : ...height
> thresholdError using gammaln
> Input must be nonnegative.
>
> Error in spm_ECdensity (line 68)
> EC(3,:) = a*exp(gammaln((v+k-2)/2)-b)*(k*t/v).^(1/2*(k-2))...
>
> Error in spm_P_RF (line 63)
> EC = spm_ECdensity(STAT,Z,df);
>
> Error in spm_uc_peakFDR (line 83)
> [P,p,Eu] = spm_P_RF(1,0,ui,df,STAT,R,n);
>
> Error in wfu_spm_getSPM12 (line 866)
> [up,Pp] = spm_uc_peakFDR(0.05,df,STAT,R,n,Zum,XYZum,u);
>
> Error in spm_getSPM (line 7)
> [SPM xSPM] = wfu_spm_getSPM12(varargin{:});
>
> Error in spm_results_ui
>
> Error while evaluating UIControl Callback
>
>
>
>
> I attached the SPM generated and the script that I have used in this
> case (in matlab format).
> The contrast in the other groups are the same, only change the vector
> values of the covariates and the scans (they are different for each
> group).
>
> Thank for help me in advance!
> If anyone need more specific information please write me!
>
--
Guillaume Flandin, PhD
Wellcome Trust Centre for Neuroimaging
University College London
12 Queen Square
London WC1N 3BG
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