From: Pieter Stouten shogi net> Date: 9 sep 2004 Subject: Pairing mechanisms: SOS versus Elo rating-based Your free subscription is supported by today's sponsor: ------------------------------------------------------------------- Save up to 67% on Omaha Steaks + Get 6 FREE Burgers and a=20 FREE Cutlery Set + Cutting Board! http://click.topica.com/= caacBBEa2i6YsbnuqMaa/OmahaSteaks ------------------------------------------------------------------- Hello shogi fans, Thomas Pfaffel and Eric Cheymol raised some interesting points about the pairing system that was used for the WOSC. First of all, the decision to use an SOS-based system was taken after careful consideration and by majority of votes of the FESA member countries. 8 members were in favour and 1 was against. 4 countries abstained. Interestingly, the countries that Thomas and Eric are nationals of (Austria and France, respectively) both abstained. The overwhelming majority in favour of SOS-based pairing does not mean that that is the right system, but it does suggest it might have some merits. Rating-based pairing within a point group of N players involves ordering players according to their rating and pairing 1 with N/2+1, 2 with N/2+2, ... , N/2 with N. What I personally do not like about that is that previous events (by means of the ratings they produce) influence the results of the current event potentially up to the very last round. Also, take two players one with a high rating (H), one with a low rating (L). At the end of the tournament it is quite possible that H's SOS is way, way higher than L's, but that H's number of wins is lower and that he therefore ends below L. By trying to equalize the SOS, that risk is reduced. The notion was expressed that somehow the player with the highest SOS gets "punished" when he gets paired with a player in a lower point group (supposedly an easier opponent). With an easier opponent the chances of winning are higher and, consequently, a player that has already had stronger opposition (as measured by SOS), has an easier chance to win than a player with the same number of points that has had weaker opposition. I think that is fair, although I understand that people enjoy beating a stronger opponent more than beating a weaker one. Another reason to opt for SOS-based pairings stems from the fact that the ESC is an integral part of the WOSC. The ESC is a knock out where 1 is paired with N, 2 with N-1, ... , N/2 with N/2+1, i.e., the nominally strongest are paired with the nominally weakest. By using SOS-based pairings, the negative effect the ESC had on the SOS of the stronger ESC participants is reduced (or maybe even eliminated). It is conceivable that ratings-based pairings cause a similar reduction, though. In summary, SOS-based pairing may or may not be better than rating-based pairing. I don't really know, but I hope I have provided some rationale for the choice that was made by the large majority of FESA members. Ciao, Pieter Your free subscription is supported by today's sponsor: ------------------------------------------------------------------- Amazing Diet Patch The fastest - Easiest way to lose weight! Try it now FREE! http://click.topica.com/= caacBBBa2i6YsbnuqMaf/MyDietPatches ------------------------------------------------------------------- --^---------------------------------------------------------------- This email was sent to: = shogi-l shogi net EASY UNSUBSCRIBE click here: http://topica.com/u/?a2i6Ys.= bnuqMa.= c2hvZ2kt Or send an email to: shogi-unsubscribe topica com For Topica's complete suite of email marketing solutions visit: http://www.topica.com/?p=3DTEXFOOTER --^----------------------------------------------------------------