student on 23 June 2008
A lot of questions are raised by this. Good points made so far by other posters are the influence of people renting the game, as well as if it only tracks plays of more than an hour. The latter point could significantly alter the data (and would explain why no game is played for less than an average of one hour... which seems unlikely).
Also, it's hard to criticize nintendo for this, without knowing how competitors would compare under comparable measurements.
