Dear FreeSurfer Team,

I processed the Group analysis by FreeSurfer 5.3.0

Our data has two groups (Patient, Control) and two covariate values (age, extra value)
mtx, contrast is 1 -1 0 0 0 0
The mris_preproc, and mri_surf2surf command were completed without error.

mris_preproc --fsgd **G2V2.fsgd --target fsaverage --hemi lh --meas thickness --out lh.**G2V2.dods.mgh
mri_surf2surf --hemi lh --s fsaverage --sval lh.**G2V2.dods.mgh --fwhm 15 --cortex --tval lh.**G2V2.dods_sm15.mgh
mri_glmfit --y lh.**G2V2.dods_sm15.mgh --fsgd **.fsgd dods --C **G2V2.mtx --surf fsaverage lh --cortex --glmdir lh.**G2V2.dods_sm15.glmdir

After mri_glmfit command, I saw the error message.

=========================================================
ERROR: matrix is ill-conditioned or badly scaled, condno = 1e+08
--------------------------------
Possible problem with experimental design:
Check for duplicate entries and/or lack of range of
continuous variables within a class.
If you seek help with this problem, make sure to send:
  1. Your command line:
    mri_glmfit --y lh.**G2V2.dods_sm15.mgh --fsgd **.fsgd dods --C **G2V2.mtx --surf fsaverage lh --cortex --glmdir lh.**G2V2.dods_sm15.glmdir
  2. The FSGD file (if using one)
  3. And the design matrix above
=========================================================

I think our fsgd and mtx compositions are equal to the g2v2.fsgd which FreeSurfer wiki example.
(https://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf2G2V)

In this situation, how can I correct my fsgd or mtx files? Is there any other command option?

Best Regards,

Han