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Hi!
I've previously run a comparison between patients and HC using qdec, but now I'd like to correct the analysis for disease duration. I've therefore generated a second qdec.table.dat file inserting the disease duration column with the following structure: fsid group duration Input subj1 1 13 Input subj2 0
(For healthy controls group (group 0) I've tried both options, leaving the duration column blank or inserting 0 as a value). I've also left the group.level file the same of the previous analysis. However, when i open the new qdec.table.dat file with qdec I get problems in correctly uploading the data. In particular, I get the following error:
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: This is the command line: mri_glmfit.bin --y /home/ospite/Pilar/freesurfer/qdec/Untitled/y.mgh --fsgd /home/ospite/Pilar/freesurfer/qdec/Untitled/qdec.fsgd dods --glmdir /home/ospite/Pilar/freesurfer/qdec/Untitled --surf fsaverage lh --label /home/ospite/Pilar/freesurfer/fsaverage/label/lh.aparc.label --C /home/ospite/Pilar/freesurfer/qdec/Untitled/contrasts/lh-Avg-Intercept-thickness.mat --C /home/ospite/Pilar/freesurfer/qdec/Untitled/contrasts/lh-Diff-1-0-Intercept-thickness.mat
Of course there is no range for the continuous variable (disease duration) in the control group, so I'm wondering how to overcome this and generate a correct qdec.table.dat file.
Thanks in advance for any help!
Pilar