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 01, 2018 12:06PM
As a follow-up question, I am running a Mixed Effects model for testing moderating effect of a risk factor X on differences in activations across three conditions of increasing difficulty, that is,

> Y(i,t) ~ t + X + t:X + (1 + t | subject)

where Y(i,t) is estimated beta at a given voxel from subject-level processing for subject i in condition at levels t=0,1,2 of difficulty. The random intercept and slope for t allow for within subject variability as a random effect. There is still variability associated with the estimation of Y(i, t). Is it appropriate to use the inverse of (se^2) [where se is standard error of Y(i, t)] as prior weights at each voxel? Would the between-subjects variance be taken care of by the linear mixed effects modeling here? The 3dMEMA.R file contains the 3dMEMA function, which allows OLS designs that do not incorporate the random intercept/slope.

My plan is to adapt these scripts to use "lmer" instead. At this point, does it make sense I use the 3dMEMA function to estimate between-subjects variance and assign weights as 1/(v + se^2), where v is estimate of variance from 3dMEMA and se is as above.

Thank you.
Subject Author Posted

3dMEMA

cmehta January 18, 2018 05:48PM

Re: 3dMEMA

gang January 23, 2018 01:39PM

Re: 3dMEMA

cmehta February 01, 2018 12:06PM

Re: 3dMEMA

gang February 01, 2018 03:35PM