 |
 |
Hi I wonder if anyone can help. I have been using the VBM8-toolbox to run a longitudinal analysis. I followed the instructions in the VBM8-toolbox manual, however I have been having trouble adding a covariate.
I have a patient group and control group, and two age groups (young and old). In total I have 49 individuals with two scans per person (98 scans total).
I put in subject as factor 1, group as factor 2, age group as factor 3 and time as factor 4.
I added the covariate as a 49x1 vector. with the covariate added the model refuses to run and I get the following error message:
Running 'Factorial design specification'
Failed 'Factorial design specification'
Index exceeds matrix dimensions
In file "/cns_zfs/system_s9_sparc/spm/spm-8-6313/spm_design_within_subject.m" (v4178). function "spm_design_within_subject" at line 81.
In file "/cns_zfs/system_s9_sparc/spm/spm-8-6313/config/spm_run_factorial_design.m" (v4537), function "spm_run_factorial_design" at line 508.
The following modules did not run:
Failed: Factorial design specification'
It runs fine if I take the coavariate out.
Am I doing something wrong here with the addition of the covariate?