It's not their data once they've sold systems to the retailers. Check GAAP and IFRS for the details. Both accounting methods are explicit in this. Business must report inventory from which they can derive units sold, usually at year's end and quarterly, however they don't have to disclose the specific units they sell. It allows business to negotiate for prices with manufacturers. Ask an accountant if you want to be completely sure about it. 

 And yes it could be possible but not 100% and not now. It's in the way these companies do business and I'm fairly sure neither one of the three manufacturers knows the correct amount of sales to end consumers. And yes, they have to rely on retailers if they want the numbers that retailers sell. 

Siras isn't installed at every retailer Nintendo sells to so even with their warranty and fraud reduction company they can still only estimate total sales.

I see what you're getting at, and it has a solid foundation in logic. The thing is, my reading of how Siras functions strongly indicates that manufacturers like Nintendo CAN track retail sales at or near 100% accuracy. I recall reading multiple sources that back up that reading. I believe ioi himself once said something similar, and he went into a bit more detail. You may wish to ask him for details.

That said, I concede that there's a possibility that I'm wrong. I sincerely doubt it, but at this point I do not have the sources to definitively prove my case, or the time it would take to track such sources down and link to them. Shall we agree to disagree on the specifics here?

 The technology is there, it can be done. However we've seen it's not done on a universal basis. I've worked as an auditor for 8 months and we're left using inventory and look at any other numbers for sales with suspicion. Retailers use their own bar codes and their own tracking and that is private to them. It could be done 100% correctly if retailers agree to use the technology and collaborate with manufacturers but so far it's not being done. Michael Pachter has also stated that Sony and MS have referred him to NPD when he's contacted these companies for those numbers, he goes on to state that these companies also use NPD to estimate retail sales (it's in a Bonus Round video at gametrailers.com). 

 You could do some research and ask these companies what the exact numbers are, it's easier if you're a stockholder. I'm fairly certain, they'll either give you an estimate or refer to another source. I've seen the technology and it works but I've seen business not doing it also, so yes I'll leave it at that. Cheers. 

Shipments. Shipments. Shipments.Shipments.

got it?

This.

There is an asterisk at the end of that "the five weeks following the last week of November 2009(*1)" that tells you what the 5 weeks are.

"*1 From November 23 to December 27 for Japan and Asia, from November 24 to December 28 for North America, and from November 21 to December 25 for Europe and PAL territories" - http://www.scei.co.jp/corporate/release/100107e.html

over a 3 million gap got it?

Going to repost this again as it appears some people missed it.

The discrepancy between VGC's reported figure and Microsoft's sold to retailer figure are the nature of the beast and not due to any intentional number fudging on the part of the site.

Here are a few key facts to consider.

1. VGC can only estimate actual sales due simply to the impossibility of tracking every single sale across the globe. The methodology is similar to that of NPD, Chart-Track/GfK, Media Create and Famitsu. Poll a portion of the retail market and extrapolate.

2. Coverage. Microsoft sells the X360 to some markets that VGC does not cover.

3. Retail channel stuffing. In 2006, 2008 and so it appears this year as well, MS pushes out as many units as possible. Even more than consumer end retail can sustain.

4. Distributors. This is an industry segment not many consider. Technically, the big 3 don't sell directly to retailers but instead to distribution companies that then sell to retail. This is why MS can ship out more product that retail is willing to buy and stock and the largest reason for big discrepancies such as this.

That.