The Official July (USA) NPD Thread (Data should be in by 6:30 PM August 23)

[Bodhesatva]

turin said:
I'm new here, and I just want to ask, What does Vgchartz do when they overstimate or understimate numbers for the consoles sales??? They adjust their numbers with the ones given by NPD??? If no, they should do that, because NPD is a reliable source

Absolutely, turin. If it becomes clear that figures are off, they are adjusted. This means that monthly totals may vary by 5-15 percent, but the lifetime totals are quite accurate. In fact, look here:

http://vgchartz.com/forum/thread.php?id=5078

As of the end of June 2007, Sony's official tracking of PS3 sales was less than 1 percent different than VGChartz' for it's lifetime. 

In other words, the monthly sales are pretty accurate. 5-15 percent off is the norm now. The lifetime sales are very accurate.