I've attempted to explain the discrpency in the Xbox 360 hardware sales in the news item I put up.
However, I suspect there will be little need for a correction in the future as
1) Mass market adoption of Xbox 360 matches hardcore adoption of the console (its under $300 now) for the holidays.
2) Hardcore gamers begin to switch to PS3 and Wii at gaming stores.
Both of those factors should result in VGC undertracking Xbox 360 in the next few months as compared to NPD (if they happened), which would bring the two closer together.
With differences in sample size there are bound to be occasional variances, but we believe our sample is sufficiently large enough to be self correcting.
For instance, the preliminary japanese data for Super Mario Galaxy was 282,500 - but then it did 37,000 the next week (~320k) .
Media Create had it at 251,000 and then 74,000 (325k).
Close, no? MC certaintly has more sources for Japan than I do for the preliminary article, but the data remains very close.
Small samples will take you to the total in a different vehicle, but if the vehicle is sturdy it usually can still get you there. You just have to be able to avoid crashing, accidents, etc.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu
