what I find funny from this discussion is how people keep saying 30 games when it's 30 exclusive and 30 multiplat so 60 per system. Still not perfect no. I also think though that those saying they should look at all games are a bit silly. If a game gets a 1 or a 4 it won't make as much of a difference to people as if it gets a 9 or a 6. Although the scores are there video game scoring has been strongly affected by an a,b,c,d,f rating system. 5 to 1 would still be an f and arguing about who gives worse fs would be kinda silly. So people focus on how they rate those that rate high to average. Yes the person who did the study could have made sure that his or her study didn't miss any by the criteria set.
The thing though is even if there is a bias. It could just be a coincidental bias or those who rate the ps3 games are harder critics. While with multiplatform games you'd get a mix of the harder critics on the ps3 and less hard ones on the 360 so the scores are lower but not as low as ps3 alone and then the 360 would be the highest (all relative to metacritic since they still are lower scores for the most part) I don't think there is some intentional harsh bias towards the ps3 games.
Now if it were to be comparing individual reviewers to metacritic that would be something else. Harder but you could then see if it's individuals or just from the combined totals
