[Freesurfer] Problem with glmfit: matrix is ill-conditioned

Hi,

Running mri_glmfit ( v5.0.0, Mac OSX10.6) I got he following 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.sib_con_cann_aangepast3.thickness.sm0.mgh -- fsgd ../../STATS/FSGD/age_gender_scan_educ_hand_cannabis/ fsgd_sib_con_cann_aangepast3.fsgd dods --glmdir lh.sib_con_cann_aangepast3.dods.sm0.glmdir --surf fsaverage lh -- C ../../STATS/FSGD/age_gender_scan_educ_hand_cannabis/ group_thickness_gender_scan_age_educ_hand_cann.mtx 2. The FSGD file (if using one) 3. And the design matrix above

Please find attached the requested files.

I noticed that rows 68 and 147 of the matrix Xg.dat are identical, and most probably caused the error. In the fsgd file I see that the correspondig cases indeed have identical values, although they are referring to different data. How to proceed?

Cheers, Ed