Author: Robert Hyatt
Date: 20:50:17 04/12/02
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On April 12, 2002 at 06:27:29, Sune Fischer wrote: >On April 12, 2002 at 00:16:35, Robert Hyatt wrote: > >>It _must_ affect both the rating of other players, and the "spread" to some >>small degree. A drop of water hitting the pond changes the depth everywhere >>as the ripples propogate around and reflect... Remember that the spread between >>two player's ratings is a statistical average of how the two players do against >>all other players in the pool. Adding a new player can change this. IE a >>player joined our local club back in 1970, and he was rated 300 points above >>me, yet I won the majority of games against him because our "styles" gave me >>an advantage... that obviously changed the spread between me and other players >>in the club, yet I did no better (or worse) against them after the new player >>arrived... >> >> > >Well as a short term effect this will send ripples up and down the ranks, but >when they have decayed and you have gone back to playing games with the other >players, you will share some of your won rating with them, or they will also >beat the new guy. >The lasting effect is just an indication of the usual uncertainties that applies >to ratings, i.e. you where actually stronger than you thought if only you were >able to increase your rating. > >The overall spread can't really change if the same formula is used, the pool >will expand or subtract to fit the formula eventually. > >-S. \ If chess were perfectly transitive that would be true, but it isn't. I've seen many cases where A beats B regularly, B beats C regularly, and C beats A regularly. When you change the pool, you can change _everything_. Because a rating within a pool factors in _all_ players within that pool. That's why absolute ratings mean nothing, and the "spread" between players in two different pools means even less... And finally, if you transplant player A and B from one pool to another both their raw ratings and the spread between them can change, easily.
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