afni.nimh.nih.gov

>groups are 23,53,27 for the anova

The degrees of freedom are calculated based on the pooled variance of all three groups:

23+53+27 minus 3 (three group averages) = 100

> 23,27 for the ttest.

This should render 23+27 minus 2 (two group averages) = 48 degrees of freedom. I'm not so sure why you got 38. Seems strange to me... Could you provide the full 3dttest++ script?

Gang