It is probably a scaling problem with using age^2. Try normalizing the age^2 column (ie, remove the mean and divide by the sum of the squares)

On 3/9/2023 3:30 PM, Triebswetter, Curtis wrote:

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Hello Freesurfer experts,

I am attempting to run the command

mri_glmfit --y lh.RBS_ADRC_N0_control.10.mgh --fsgd RBS_ADRC_APOE_age22.fsgd dods --C APOE_ageINT.mtx  --surf fsaverage lh --cortex --glmdir lh.RBS_ADRC_N0.glmdir

On this .fsgd file:

“RBS_ADRC_APOE_age22.txt”

Using the following design matrix:

“lh.RBS_ADRC_N0.txt”

I am receiving the error message:

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ERROR: matrix is ill-conditioned or badly scaled, condno = 1e+08

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Possible problem with experimental design:

Check for duplicate entries and/or lack of range of

continuous variables within a class.

I would appreciate your insights into what may be the likely cause of this error and apologize that the files are in text format. If need be, I can convert these to their proper formats.

misc information:

Freesurfer 6.00

CentOS v7

Best,

Curtis

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