Dear SPMers,
another statistics question...
If I want to look at the effect of age between two different groups (e.g.:
healthy controls and schizophrenics) which model is the best to choose? (I
tried "PET-models: multi-subject: covariates only", selected 2 subjects (2
blocks for 2 groups) and entered for each block the appropriate scans. Then,
I entered age as covariate of interest.). The contrast "1 -1" yielded
GM-density increments with age in group A and GM-density decrements with age
in group B. What contrast (+masking?) should be used when looking for a
group difference in GM density decline with age? Is there any other
solution for addressing this question ?
Any help would be greatly appreciated.
Best Regards,
Nikos Koutsouleris
Neuroimaging Workgroup
Department for Psychiatry
Univ. of Munich, Germany
Tel: ++49 89 5160-5717
|