I'm gonna just say that it's accurate enough. If Super Mario Galaxy has sold 8.01M or 7.36M, does it really matter? Sure, it's better to have completely accurate numbers, but it doesn't really matter. You can't really see something of a trend depending on whether it sold 7.36M or 8.01M.
The only thing that is lacking, is European numbers. Not having them on certain games makes you wonder "did it sell 475K with Europe numbers, or 700K with Europe numbers?". That's a large difference. All in all, games that have data from the all the big 4 areas have accurate enough data.
When I write Fact: in one part of the post, and opinion: (or a similar word), it's not because I can then say "my opinion can't be wrong". It is to inform what part is pure facts, and which part I try to draw a conclusion in.
