I“m no statistician but I've heard a lot about raw numbers and attach rates and the argument that developers really only care about total sales however they get there.
One factor that doesn't seem to be getting much attention is development costs. Total sales no matter what the numbers don't mean a hell of a lot if you don't make a profit. There is a big difference in what console you develop for.
The DS is the least expensive with an average of about $1m per game. (Pretty damn good return on Nintendogs) and the PS3 is the highest reported to be an average of $15M. The Wii falls between but at least 1/2 and probably closer to 1/4 the costs. Wii games can and have made decent profits on 200,000 to 300,000 sales but apparently any HD game with less than 500,000 is a serious disaster. Haze certainly comes to mind.
It's a good thing that GTA4 sold 10M games because they had a $100M nut, not to talk about marketing, dealer discounts and all the rest.
My point is that when you go talking about sales and attach rates and all that good stuff, you have to realize that the cost of making that game is an important factor also. The difference between 300,000 sales in a Wii game and 300,000 sales in a PS3 game can be the difference between a bonus and a pink slip.
