AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

History of AFNI updates  

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February 13, 2017 02:38PM
Dear experts,
I am a little confused regarding the degrees of freedom (DOF) and their relevance for seed-based functional connectivity.

  1. After a regression analysis (e.g., the removal of M confound variables in a GLM), what are the DOF of the residual timeseries (i.e., errts)? Are they simply the number of time points or we must subtract to it M, that is, the number of regressors in the model?
  2. Assuming that the latter is true, what happens when we compare timeseries that have been through different models (due to censoring or to different regression matrix)? I would say that the r-values of a correlation analysis should be transformed in z-score = z-fisher * sqrt(dof-3) as it is done in www.pnas.org/cgi/doi/10.1073/pnas.1301725110. However, this does not seem a common approach, surprisingly even when censoring is used!
Thanks
Best
Daniele
Subject Author Posted

Degree of Freedom

mallow February 13, 2017 02:38PM

Re: Degree of Freedom

gang February 14, 2017 08:48AM

Re: Degree of Freedom

Phil Burton February 14, 2017 02:02PM

Re: Degree of Freedom

gang February 14, 2017 03:46PM

Re: Degree of Freedom

mallow February 15, 2017 03:52PM