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Hello FreeSurfer Developers,
I’m attempting to compute mri_glmfit to correlate cortical thickness with
my dependent var while controlling for age, gender, iq and MRIcenter (2
centers). I don’t have any interactions or assumptions on group differences
so I am using DOSS design (with fsgd file)
I have two questions regarding the analysis, which I couldn’t find in the
archives ( I copied the error and attaching the fsgd file)
When I am trying to control for the different variables using 4 classes
(Center1Female, Center2 Female, Center1Male, Center2,Male) (Correlation
matrix 0, 0 , 0 , 0 , 0, 0, 1) I am getting the error:
ERROR: matrix is ill-conditioned or badly scaled, condno = 1e+10
--------------------------------
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.bin --y lh.ext.thickness.10.mgh --fsgd EXT2.fsgd doss --C
EXT2.mtx --surf fsaverage lh --cortex --glmdir lh.ext2.glmdir
2. The FSGD file (if using one)
3. And the design matrix above
Attempting to diagnose further
SumSq: Min=0.000000 (col 1), Max=0.000000 (col 0)
Column 1, all values are 0
--
However when I am not using the 2 sites as classes and using just the
gender as a class (0,0,0,0,1) everything runs without errors. Is there any
other way to control for the MRIsite?
Thank you for your help with this matter
Best wishes
Michal
--
Michal Tanzer, PhD
Postdoctoral fellow; Clinical Psychologist.
Research Department of Clinical, Educational and Health Psychology,
University College London,
United Kingdom
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