Dear AFNI experts,
I try to run 3dICC on ‘very preliminary data’ (so very small sample size).
I would like to quantify networks similarity across 3 subjects.
3dICC -prefix myICC -jobs 4 \ -mask mask.nii.gz \ -model '1+Network+(1|Subj)' \ -dataTable \ Subj Network InputFile \ s1 N1 thresh_zstat13.nii.gz \ s1 N2 thresh_zstat8.nii.gz \ s2 N1 thresh_zstat17.nii.gz \ s2 N2 thresh_zstat13.nii.gz \ s3 N1 thresh_zstat9.nii.gz \ s3 N2 thresh_zstat10.nii.gz
When I ran 3dICC, it failed:
***** Summary information of data structure *****
3 subjects : s1 s2 s3
6 response values
2 levels for factor Network : N1 N2
Contingency tables of subject distributions among the categorical variables:
***** End of data structure information *****
Reading input files now…
Range of input data: [-6.717, 14.814]
If the program hangs here for more than, for example, half an hour,
kill the process because the model specification or something else
is likely inappropriate.
 “Great, test run passed at voxel (21, 43, 23)!”
Error in asMethod(object) : not a positive definite matrix
Calls: nrow … asMethod → as → .class1 → as → asMethod → as → asMethod
Do you have any idea about why it failed?
Many thanks in advance.