mrstickball on 17 April 2009
sparkit -
NPD works by obtaining data from approximately 60% of US stores. They use this data, and extrapolate the rest for their monthly charts. Media Create and Famitsu report similar numbers as well.
NPD does make corrections once in awhile, but they do not report them. NPD has been wrong before, but some here tend to think that if NPD disagrees with their favored system, it's NPD's fault. NPD is right 95% of the time. There are errors, but I'd take NPD over VGC, since VGC tracks maybe 1/10th the retailers that NPD does.
That's not to say VGC is bad, but inaccurate compared to NPD at the moment.
Back from the dead, I'm afraid.
