We are new to Freesurfer. We appreciate your help & apologize if the question is simple.

We need cortical thickness in lobes instead of parcellates. Is it correct to take the average of the parcelates from the aparc+aseg.stats file under subjid/stats folder. For example, 

cortical thickness of frontal lobe = sum of frontal parcellates  divided by number of parcallates .

Do we need to do any correction such as weighing the surface area measurements ?

Thank you 

James