Hi Afni Experts,
We ran 3dttest++ -resid -clustsim on a 2x2x2 MNI grid. The outputs from this stated a minimum cluster of 650 voxels for a p=0.005,alpha=0.05. An error of wrong FD also appeared in the terminal even though the command line processed through to the end.

When running the 3dttest++ residuals with 3dFWHMx -acf and then with 3dClustSim we got 150 voxels for p=0.005, alpha=0.05 with -acf flag selected.

1) Does 3dttest++ -resid -clustsim automatically use -acf option when calculating smoothness (version downloaded approx 2 weeks ago)?

2) Is there any reason you could think of as to why the estimates are so far off when the same MNI template mask and residuals are in both scenarios?


Thanks,
Ajay