Hello,

I’ve read in the 3dclustSim help output the issue that can arise from trying to find a cluster size for a given with small ROI masks, p, alpha combination. I'm wondering though, what AFNI users do to circumvent this issue? In SPM I know pit is typical to apply RFT with a certain z score cut off. But I haven't been able to find how one might go about that in AFNI. The context of my particular issue is explained below.

I'm using 3dClustSim to ascertain a cluster size threshold when using an ROI mask of 12 ROIs in my resting state connectivity analysis. These are bilateral, and given the homotopic nature of the regions, I treated the bilateral seeds as combined in terms of multiple comparison (thus having 6 total comparisons). A straight Bonferroni correction (with 6 comparisons) would say that anything which passes a p threshold of < 0.008 would be significant. And indeed, if I just 3dmaskave the values from the z transformed connectivity maps and run a simple one sample t test I can find which seeds pass this threshold. But that is ignoring the issue of correlation among regions, which violates an assumption of independence for Bonferroni.

Thanks in advance for the help!

Sam DeWitt