There are plenty of trusted research organisations such as the NPD Group, GfK, IHS, IDG & more who track the video game market very accurately using a mix of point of sale tracking and external research. Platform holders and other organisations subscribe to this data which is highly accurate and provide an overview of the video game market. 

On VGChartz the numbers do not match to these other trackers and whilst some game sales tracked here are somewhat close, the majority are hilariously off. I can say that with a good amount of authority. Brett has been known to make up and inflate sales numbers before back when he was a member on Neogaf and has been caught lying about the methods he uses to track video game sales. He does not have any access to POS data either. With regards to Japan he takes Media Create and Famtisu numbers, in regards to the USA he takes NPD leaked figures and worldwide he uses a variety of public sources and tips in order to "track" sales. Even with this data, it's not enough to provide an accurate understanding of the market, nor is it worth charging for. Especially when every single month the US sales here differ drastically from actual NPD sales figures and this site is very much known for adjusting its data constantly when caught out by a public or leaked sales update from an official source. 

Let me give you an example, Madden NFL 07 was a launch game for the PS3 and the sales on VGChartz are actually fairly close to the actual total sales. I assume Brett was able to get a leaked number on this. Now when you look at GRID for PS3/360 the sales are hilariously off in the US. Like so wrong!

I do have to commend Brett though, he's certainly been able to turn this site into an authoritative mouthpiece for video game sales and it's funny to see how many people take the numbers posted here as gospel or use them to discuss sales of titles. One of the funniest things I've seen here was when PS4 sales were lower than what Sony said and Brett couldn't work out where they came from, even going as far as to imply that Sony could be wrong. Not exactly what you want to hear from a tracking site that is suppossed to have this data in the first place.

We're going to see a similar adjustment happening to the Wii U very shortly as well (down).

@mods- I backed up my original point in this post so this isn't breaking any rules. Please PM me if you think it is. 

 I never heard of GFK, IHS and IDG in any game related media, quotes or used as a source. NPD is only good for the states and UK's sales numbers. No one else tracks worldwide numbers.

Again, why are you here if you don't like the sales tracking?

You've never heard of GfK Chart-Track? Or IHS and IDG? Well.... that says a lot doesn't it. Sony, Microsoft and Nintendo subscribe to them as does pretty much every organisation within the video game industry. If you don't know what you're talking about then why even bother trying to defend the site? 

The reason I joined here was to participate in the COMG pre order thread. I never joined here for the bogus sales numbers. 

You've never heard of GfK Chart-Track? Or IHS and IDG? Well.... that says a lot doesn't it. Sony, Microsoft and Nintendo subscribe to them as does pretty much every organisation within the video game industry. If you don't know what you're talking about then why even bother trying to defend the site? 

The reason I joined here was to participate in the COMG pre order thread. I never joined here for the bogus sales numbers. 

I knew there was a reason you wear a bra! Oh, and Sony is a subscriber to VGChartz Plus, because I told them too.

Like I said, I haven't seen any mention of those in any game related media, blogs, forums, gaming magazines, ect.  You sound a bit like a disgruntled former employee with this site with your repeated criticisms of it. You barely post in the COMG pre order thread.