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  

Previous Message Next Message
Message List New Topic Print View
|
gang
July 26, 2015 11:38AM
> why is it better to center outside of AFNI for this analysis as opposed to centering within AFNI?

Dominic,

For easy interpretation, your model can be formulated as the following,

Y = (Age - mean_Age) + (Anxiety - mean_Anxiety) + (Age - mean_Age) * (Anxiety - mean_Anxiety) + other stuff

The subtlety here is the term (Age - mean_Age) * (Anxiety - mean_Anxiety), which usually does not center around its own mean. I hope this explains why it would be better to center yourself before plugging in those terms in the program.

Gang
Reply Quote
RSS
Subject Author Posted

3 way interaction 3dttest++

dsf215 July 24, 2015 11:38AM

Re: 3 way interaction 3dttest++

gang July 24, 2015 04:15PM

Re: 3 way interaction 3dttest++

dsf215 July 24, 2015 04:31PM

Re: 3 way interaction 3dttest++

gang July 26, 2015 11:38AM

Re: 3 way interaction 3dttest++

Emperor Zhark July 28, 2015 12:38PM

Re: 3 way interaction 3dttest++

dsf215 July 28, 2015 11:18PM