Forest,

You surely know statistics better than I do, so let me ask something I've been wondering about for some time. It even somewhat ties into the subject you've been discussing.

Say you want to find out who's the best player (team, etc) in a round robin tournament. However, arranging matches is expensive, mainly in time. So you want to pair two players (teams, etc) against each other just enough to be able to decide who is best.

How would you do this?

It seems you could decide upon a confidence level and then have a given pair stop playing once you're confident that one of the players in question beats the other player. The level would then be picked so that one is reasonably sure that all pairwise contests "point the right way" (have the right winners). That would be conservative, since methods don't necessarily use all the information of every contest.

It gets more difficult when one takes ties into account, though. For most games, no pair is exactly tied in the long run, but one could imagine a game where if both players cooperate, there's always a tie (such as two players in chess agreeing to always do a grandmaster draw, based on tit-for-tat reasoning). Then a long run of ties would in itself be significant: it means that neither player is (or chooses to be) any better than the other. Just eliminating ties from consideration, as you did in the winner calculation, wouldn't work because it could take a really long time before a non-tie result is granted.

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