Hello,<div><br></div><div>I am analyzing cortical thickness in a patient and control group. I have two covariates: age and length of disease. I am using the model from:</div><div><br></div><div><a href="http://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf2G2V">http://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf2G2V</a></div>
<div><br></div><div>However, for the control group I put length of disease as 0 in my FSGD file. When I run the GLM, I get the following error message:</div><div><br></div><div>matrix is ill-conditioned or badly scaled, condno = 1e+08</div>
<div><br></div><div>Can you please tell me what I am doing wrong? Below is the required information.</div><div><br></div><div><div>1. Your command line:</div><div><br></div><div>    mri_glmfit --y lh.disease_length.thickness.20.mgz --fsgd fsgd_disease_length.txt dods --glmdir lh.disease_length.thickness.20.glmdir --surf fsaverage lh --C groupdiff_length_disease.mat </div>
<div><br></div><div>  2. The FSGD file</div><div><br></div><div>GroupDescriptorFile 1</div><div>Title Anorexia vs Controls</div><div>Class Control plus blue</div><div>Class Patient circle green</div><div>Variables Age Disease_Length</div>
<div><br></div><div>Input C07 Control 37 0</div><div>Input C28 Control 28 0</div><div>Input C39 Control 37 0</div><div>Input C54 Control 40 0</div><div>Input C57 Control 32 0</div><div>Input C10 Control 54 0</div><div>Input C33 Control 31 0</div>
<div>Input C29 Control 22 0</div><div>Input A01 Patient 39 20</div><div>Input A02 Patient 24 11</div><div>Input A03 Patient 35 15</div><div>Input A04 Patient 40 10</div><div>Input A05 Patient 35 20</div><div>Input A06 Patient 57 20</div>
<div>Input A07 Patient 31 16</div><div>Input A08 Patient 20 8</div><div><br></div><div>  3. And the design matrix</div><div><br></div><div>Design matrix ------------------</div><div> 1.000   0.000   37.000   0.000   0.000   0.000;</div>
<div> 1.000   0.000   28.000   0.000   0.000   0.000;</div><div> 1.000   0.000   37.000   0.000   0.000   0.000;</div><div> 1.000   0.000   40.000   0.000   0.000   0.000;</div><div> 1.000   0.000   32.000   0.000   0.000   0.000;</div>
<div> 1.000   0.000   54.000   0.000   0.000   0.000;</div><div> 1.000   0.000   31.000   0.000   0.000   0.000;</div><div> 1.000   0.000   22.000   0.000   0.000   0.000;</div><div> 0.000   1.000   0.000   39.000   0.000   20.000;</div>
<div> 0.000   1.000   0.000   24.000   0.000   11.000;</div><div> 0.000   1.000   0.000   35.000   0.000   15.000;</div><div> 0.000   1.000   0.000   40.000   0.000   10.000;</div><div> 0.000   1.000   0.000   35.000   0.000   20.000;</div>
<div> 0.000   1.000   0.000   57.000   0.000   20.000;</div><div> 0.000   1.000   0.000   31.000   0.000   16.000;</div><div> 0.000   1.000   0.000   20.000   0.000   8.000;</div><div>--------------------------------</div>
<div><br></div></div><div>Thank you,</div><div>Allie</div><div><br></div><div><br></div>