In a normal statistical sense - margin of statistical error being constant - higher selling games would have a higher number of overtracking/undertracking due to their higher overall numbers, therefore - with the statistical margin of error being constant - higher sales - higher number of sales under/overtracked.
Just so I understand how things work here though-
If a game is on PS3 = UNDERTRACKED, USUALLY MASSIVELY
If a game is on 360 = NOT UNDERTRACKED - POSSIBLY OVERTRACKED
I think that's how it goes - correct me if I'm wrong.