Hello Freesurfer Experts!

I met the  mri_glmfit error:  matrix is ill-conditioned or badly scaled, condno = 1e+08.I am trying to run a 8 group 3 variables analysis: with diagnosis being my
variable of interest and trying to regress out the effects of gender,background,age,education and seizure.

  1. Command line:
      mris_preproc --fsgd qdec/group.fsgd --cache-in thickness.fwhm10.fsaverage --target fsaverage --hemi lh --out lh.thickness.fwhm10.groups.mgh

       mri_glmfit --y lh.thickness.fwhm10.groups.mgh --fsgd group.fsgd dods --C Difference.group.mtx --surf fsaverage lh --cortex --glmdir fwhm10.thickness.glmdir 

  2. The FSGD file (see attached)
  3. And the design matrix:
     1 1 1 1 -1 -1 -1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0    (or see attached)

I encounter this error. I have no idea how to proceed.Is all this because I have too many covariates?
I am looking forward to your response!
Thanks,


Kan