Mummelmann on 10 January 2012
Shipped or sold? Has vgchartz really undertracked by over 1.5 million WW? I don't think that this is possible, Brett has come a long way since the start of the site and has been fairly accurate lately.
The 18 million Kinect units are shipped to retailer at any rate so it is quite likely that the hardware numbers are the same.
I would laugh my ass off if it turns out that MS stuffed the channels! 
Essay Pro