Why are ratings calculated by tournament instead of by game? When you go to a chess tournament, why is your rating calculated by your tournament performance instead of how most internet chess servers do it? Why don't they adjust the rating by game? What is the advantage.
The way that rating systems work, your most recent results have a greater influence on your rating than your earlier results. So if your rating was adjusted after each game in a tournament, then the games in later rounds would affect your final rating more than the games in the earlier rounds. Most of the time this wouldn't make much sense, as a tournament usually takes place over a fairly short period of time. It makes more sense to adjust the rating just once, after the tournament has finished, with all games counting equally.