its pretty obvious that vgchartz is towards the bottom of the list when it comes to accuracy.(When compared to NPD/media create/Chart-Track/Famitsu)
Considering we can view almost all the sales data for free I'm perfectly fine with dealing with that, though I will obviously sometimes complain when a more reputable tracker has numbers that are very different from vgchartz.
All these companies basically extrapolate data from stores they track, and while that works well on games that are selling a lot, sometimes it doesn't work well on smaller titles.
We can see that easily by comparing how different media create and famitsu numbers are for games that sell under 10k. Sometimes media create has a game selling twice as much as what famitsu has. So basically none of these tracker are 100% accurate, unless I am mistaken and one actually takes sales data from every single store that sells games.
