I want to calculate the significance of grayvol between two groups, but the data i noticed in the 'lh.aparc.stats' file shew some problem.The pic below shows the grayvol of entorhinal of some subjects,but one of them appears to be 136,far more lower than the others, what's the problem? is it a normal systematic error or is there something wrong with my operation while calculating? The same situation is also found in CurvInd and FoldInd.