I have 2 groups (group 1 = 3 members, group 2 = 12 members) and I did like to regress out the effects of groups + other variables by using doss. However, whenever I specify doss with the mri_glmfit command, it gives me an error message (see below). I saw that others have experienced similar issues without any solutions. How can we solve this? Any insight is appreciated. 

Best,

Paul

mri_glmfit command:

mri_glmfit --y ../../freesurfer/subjects/tracula_output/stats/mcp.avg16_syn_bbr.FA.nii.gz --fsgd dti_RPQ_3.fsgd doss --C dti_RPQ.mtx --o mcp_FA.glmdir --save-eres --nii.gz

design.mtx:

0 0 0 0 0 0 0.5

Terminal output:

gdfRead(): reading dti_RPQ_3.fsgd

INFO: DeMeanFlag keyword not found, DeMeaning will NOT be done.

Continuous Variable Means (all subjects)

0 Age 46.9333 9.86216

1 Sports 0.0666667 0.249444

2 Games 1.13333 1.62754

3 Days_TBI 1903.2 907.81

4 RPQ_3 7 2.28035

Class Size and Means of each Continuous Variable

1 PPCS_Male  3  33.3333   0.3333   2.3333 1337.3472   6.6667 

2 PPCS_Female 12  50.3333   0.0000   0.8333 2044.6632   7.0833 

ERROR: Class PPCS_Male has 3 members. With 5 variables and using DODS, you need at least 6 members