[Freesurfer] GROUP ANALYSIS ON QDEC

Hi, I've done the recon-all for all my subjects, and everyone ended with no errors. First of all, I don't understand if the recon-all do a volume normalization: why subjects have different number of vertex?if the comparison isnt't vertex by vertex, how is it done? Now I want to do a group Analysis using QDEC, so I've done the recon-all -qcache to create a common space for my subjects. I would know how I have to set parameters in the DiSPLAY and how can I use the "correction for multiple-comparisons" to see the results of my analysis. Is there a way to have all the values of the cortical thickness vertex by vertex and not only the average? Sincerely,

Luisa Leo