More ignorance from someone on a reputable videogame site talking about VGChartz.
As always I will post this - Why it is so Easy to Blame VGChartz
"What VGChartz offers is timely data that isn't meant to be 100% accurate but be in the right range. We don't compete with the likes of NPD, GFK or ChartTrack; we offer a service that is totally different. One that is not based on comprehensive and direct retail tracking, but rather uses modern and alternative methods to quickly arrive at estimates, combined with a database of historical sales - constantly adjusted and tweaked to be as accurate as possible."
"However, even with the greatest of diligence, our data is still just an estimate so whenever quoting a figure from VGChartz it should be listed as an estimate and readers should be made aware that there is a margin of error associated."
And of course, link to the methodology page - http://www.vgchartz.com/methodology.php