On 01/24/2014 11:54 AM, Natasha Haris wrote:

Dear Freesurfers,

I am slightly confused about the monte carlo simulation.

First off, I only find a blob when I run the p<0.05 threshold level and don't see anything else when I run simulations with p less than that. What does this mean?

Which threshold level? clusterforming/voxelwise or clusterwise? If clusterwise, then it just means that you have a cluster whose p value is just under .05 so you lose it by going to a more stringent threshold.

Additionally, when I click on any question of interest after running this p<0.05 simulation (for ex. "Does the average thickness, accounting for Group, differ between male and female?" I get the same blobs that I found before I ran this precomputed simulation. Is the simulation not running correctly? Am I supposed to enter this threshold value (1.3) into the area marked Threshold min= and max=5.

Are you sure it is exactly the same? Look to see if there are some very small blobs that disappear. Otherwise, it may be that the blobs you have are all significant.

Thank you for your help! Natasha _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer