All these sales numbers that get vomited out by game companies who are basically say "Whee look at all the stuff we sold, we rock!", do they take into account the install base when comparing sales numbers from earlier generations?
For example, if an NES game only sold 400,000 copies, but the install base for the system 500,000 units and a PS2 game sells 1 million, but the install base is 5 million is the PS2 game really more of a success? And that's not even taking into account profit margins.