The sales data is often adjusted to closer reflect NPD numbers.

No one really knows where Vgchartz gets their data. However,most of the time Vgchartz's numbers are similar to NPD.If they aren't,the numbers get adjust to reflect NPD's data.

Street Fighter IV will most likely be adjusted to reflect NPD's numbers.

Webmaster or MOD told me on this thread http://www.vgchartz.com/forum/thread.php?id=64244&page=1 and i thought they're NPD group.

Vgchartz is a fanboy site,

but they try to do their best to be as much possible accurate.

They do a great work in order to be accurate, they sum up the datas from all over the world, but they don't have the power (but who knows a day) to buy datas directly from NPD and Gfk.

And take in account that if they were wrong, they adjusted the numbers in order to match the informations. (with the exception of australia and the f.. missing 75k for the ps3 and the bravia deal ;) )

This would have been a good comment, expect for that odd first sentence.

Vgchartz is a broad look at the market. And it adjusts things overtime. Most of the time its pretty accurate especially in regards to hardware sales.

So, once again NPD figures are wrong but VGchartz is righter I guess. How that is possible with just 2% of samples against over 60%, only god knows this...

The dude Brett does a very decent job considering all the markets he covers. NPD is an entire firm that only covers America. NPD will always be more acurate.

Oh, I thought you were talking about the title... IV instead of 4...

*leaves*

I'm pretty sure VGC gets a small amount of data from different retailers and extrapolates that data for the whole region.

NPD's data is taken from the majority of retailers in America, therefore making it a lot more reliable.