The DOF is determined only from the design matrix as
DOF = #RowsX - #ColsX
So, it would be 9 regressors, not 6
On 9/26/2019 12:31 PM, cody samth wrote:
External Email - Use Caution
Hi I have a question regarding how freesurfer calculates the degrees of freedom
when you have three groups in the FSGD/contrast files but are running analyses
on group A vs C.
For example I have an analysis with 3 groups and 2 covariates. My primary
question is: is there a difference between any groups. Which I have the
contrast:
1 -1 0 0 0 0 0 0 0
1 0 -1 0 0 0 0 0 0
When I write a contrast for A vs C: (1 0 -1 0 0 0 0 0 0) Does freesurfer
consider this model as 9 regressors? Or 6 regressors; which would be present in
a typical group 1 vs group 2 analysis that could be modeled by (1 -1 0 0 0 0)
if group B didn't exist?
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu<mailto:Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
