Hello,

I am using 3dttest++ to explore associations between seed-to-voxel resting state connectivity and scores on a performance-based assessment of function in a sample of patients with schizophrenia. I am using the recommended -Clustsim option in 3dttest++ to use the permutation method to simulate the noise volume to identify clustersize thresholds for a set of voxelwise p-values. I was hoping to also try the recommended 3dClustsim -acf method to see if it yields similar cluster-size thresholds. Even though I used AFNI to perform the seed-to-voxel analyses, the data was pre-processed using Data Processing Assistant for Resting State fMRI software (DPARSF; [rfmri.org]). Given this, I am not sure of the three estimates to pass to the -ACF function. I gathered from this exchange on the message board (https://afni.nimh.nih.gov/afni/community/board/read.php?1,155089,155114#msg-155114) that this approach for cluster thresholding may not be valid if the data was preprocessed outside of AFNI (since afni_proc.py outputs these blur estimates for each subject). Is this right?

Can I use this method (3dClustim -acf -mask) if my data was processed using other software? If so, how do I obtain valid blur estimates for a given subject? I've been playing around with running 3dFWHMx -mask -acf, but wanted to ask these preliminary questions before I went any further. Thanks!

~Steph