NPD is not accurate ( partly )

[Mr Khan]

kirby007 said:

Torillian said:
I guess your issue then is that you have absolutely no NA consumer sales data that's better than NPD. Even the first party companies will just cite NPD when they talk about consumer sales in NA so there really isn't any source for more accurate information and all you could say is how many units things shipped.

there is a difference between using it as guideline or believing it is 100% correct

If you've worked in statistics, you tend to understand that as long as the sample size is large enough and you are being unbiased in which retailer you choose (which is where NPD kind of falls off. Don't they not track Walmart for video games?), you can have the sample reflect reality. With a large sample, you can state with a high degree of confidence that the "real" value is about X, plus or minus a margin of error.