http://www.gamesetwatch.com/2008/06/analysis_what_vgchartz_does_and.php#more
this is the original article they were referencing. id like to see a reply from VGChartz.
what it is people take numbers way to seriously. even if this website doesn't have sources. NPD doesn't have Wal-Mart. the biggest retailer in america. how can NPD numbers be any more reliable than VGChartz.







