http://kotaku.com/346135/halo-3-beats-out-wii-play-for-best-selling-video-game-of-2007

so the main news about the above article of Halo 3 beating Wii play is not what i care about.  One thing that struck me as odd was the CoD 4 numbers.  If NPD numbers are correct, then VG has it undertracked here by A MILLION units.  Now, does NPD only track sold to retailers?  Im not sure, but the article somewhat implies that its numbers sold to customers with  the statement "it sold ... to the masses"

 If it were to retailers, though, how likely is it that theres a million CoD 4s for Xbox 360 out there waiting to be bought up?  seems odd considering its actually been kind of hard to find a copy of the game for either PS3 or xbox 360 recently.  

 So whats the deal with these numbers?  I can understand maybe being under/overtracked by like 150K for software, considering percent errors and what not, but have a -/+50% error is a little ridiculous. 

Thoughts? 

no, npd tracks what vgcharts does, vgcharts just had one of the biggest underestimated trackings in its history id say

Walmart.

Somebody speculated, I believe possibly correctly, that Ioi misinterpreted the market for CoD4 and as such his estimations for it were based on hardcore rather than casual gamers. Obviously it has appealed to the casual market (casual as in last gens PS2 market, not casual as in WiiFit) and as such his estimations for the major retailers were a mile off.
Of course NPD does not have access to Walmart numbers either and they must have been very bullish on the sales in those areas to get such a larger difference. Personally I believe the number is probably well over a million but quite short of the NPD number.

I doubt walmart were the primary sellers for this one, it had a LOT of deals going around at places like target and gs.

Yeah, i remember just after christmas, CoD was on sale for about 38 bucks at target. These numbers just seem to be really off. Think its just one or the other is horribley wrong, or one estimated under while the other estimated over?