Hi,
I am analysing structural data with mri_glmfit. After pre-processing I have first used one group variable (gender) with one covariate age. I had no problem processing the data and visualising it in tksurfer.
I then tried to add another covariate (measure of immediate recall). So I had in total one group variable and two covariates. I reanalysed the data but got the following error:
FixVertexAreaFlag = 1 UseMaskWithSmoothing 1 OneSampleGroupMean 0 y /media/storage2/proc/freesurfer/60_w2/checked/analysis/lh.gender_age_immrec.thickness.10.mgh logyflag 0 usedti 0 FSGD gender_age_immrec_fsgd.txt glmdir lh.gender_age_immrec.glmdir DoFFx 0 Creating output directory lh.gender_age_immrec.glmdir Loading y from /media/storage2/proc/freesurfer/60_w2/checked/analysis/lh.gender_age_immrec.thickness.10.mgh Matrix condition is 12866.7 ERROR: matrix is ill-conditioned or badly scaled, condno = 12866.7 Possible problem with experimental design: Check for duplicate entries and/or lack of range of continuous variables within a class. 0.000 1.000 68.000 10.000; 1.000 0.000 65.000 5.000; [trunkated the fsgd file output but it is the same as the one used for the sucessful analysis except for one extra column]
After this error I thoroughly checked all my files but could not find anything wrong. So to check I could do an analysis using the extra variable I did another analysis with gender and immrec. This worked without problem.
I have attached all my fsgd files and mat files. They all use the same subjects and gender info and only differ by one column. Since permutations worked I cannot fathom why it does not work when all put together.
The mri_glmfit syntax used for each analysis was:
mri_glmfit --y lh.gender_age_immrec.thickness.10.mgh --fsgd gender_age_immrec_fsgd.txt doss --glmdir lh.gender_age_immrec.glmdir --surf average100 lh --C gender_age_immrec.mat
mri_glmfit --y lh.gender_immrec.thickness.10.mgh --fsgd gender_immrec_fsgd.txt doss --glmdir lh.gender_immrec.glmdir --surf average100 lh --C gender_immrec.mat
mri_glmfit --y lh.gender_age_immrec.thickness.10.mgh --fsgd gender_age_immrec_fsgd.txt doss --glmdir lh.gender_age_immrec.glmdir --surf average100 lh --C gender_age_immrec.mat
I use 4.01 (but also checked with 4.02) under Ubuntu 64 bit on a Xeon machine.
Thanks very much for your help
Nic