Everywhere you go you are viewing the same thing. Someone's best attempts at "guessing" the actual end result using various methods. VGC uses the same methods NPD does, just on a smaller scale (NPD has more retail sources basically). The truth is no one is perfect.
Example, if you add up what NPD says the big 3 sold during the last quarter of 2007 they are way off. Whereas VGChartz is much closer.
The only reason people, like your friend, use NPD so much is because they have been around longer and have become the defacto leader in sales charts.
Tell your friend to do this. In the next couple of weeks all 3 companies will detail their fiscal year results. Compare those SHIPPED figures to VGC's SOLD figures and you will see that VGC is spot on.
Whenever you look at the numbers from NPD, Mediacrate, famitsu, VGC, etc just know that they are all approximations and in reality are giving you a general idea of what is happening.
You're friend is just being a fanboy because VGC doesn't give him the answer he is looking for.







