John Kirk took a look at Android numbers from IDC and a new approach to measuring Android activations by Google. Neither data set was found to be satisfactory, and Mr. Kirk's opinion is that Google’s New Android Math Doesn’t Add Up. He also called for firms like IDC to stop counting all Android sales as "Android" sales, and instead to count only those sales that contribute to the platform as a whole, and to divide out Android variants in China, Kindle Fire sales, and perhaps even Android devices running Facebook Home. It's a very good read.
Check It Out: Thinking Differently About Android Numbers