Author: Christoph Fieberg
Date: 12:21:04 07/10/01
I refer to to description of my program which simulates the result of a chess game given under http://www.icdchess.com/forums/1/message.shtml?178041 Deeper analysis showed amazing facts: The advantage playing White for the weaker player is often twice as high as for the stronger player given the same rating difference! In case the rating difference is 50 – 170 points I found that the advantage is 20 - 31 Elo-points if White is the stronger player but 43 - 60 Elo-points if Black is the stronger player. (Example: 2500 – 2350: adjusted difference is 2510/2515.5 – 2340/2334.5; but for 2350 – 2500: adjusted difference is 2371.5/2380 – 2478.5/2470) In case the rating difference is more than 170 points the advantage is 20 – 46 Elo-points if White is stronger and 43 – 87 if Black is stronger. However, for a rating difference below 50 points it seems that there is not such an effect any more. I found that with about 85% likelihood the advantage is 21 – 56 Elo-points and with 15% likelihood the advantage is 0 – 79 Elo-points for both cases (White player stronger, Black player stronger). The second amazing fact is that I did not find that the conditioned draw percentage (depending on the success rate) dropped below 50% and that in case the higher rated player plays White the conditioned draw rate is somewhat higher than if the lower rated player plays White. I found a value in the range of 60% - 68% in case the rating difference is more than 50 Elo-points and the stronger player plays White. If the weaker player plays White the value is in the range 53 – 65%. For a difference below 50 Elo-points the value is 50% - 68% idependingly whether the stronger player plays White or not. Example: Analysis of 9806 games with White 2570-2670 and Black 2370-2470 => average 2598 – average 2427, rating difference 171 Elo-points Results: 1-0 = 60.45%, ½ =31.37%, 0-1 = 8.18% => conditioned draw rate = 65.73% (Success rate = 76.14%, Elo advantage White = 30.6 points) comparing to analysis of 9403 games with White 2370-2470 and Black 2570-2670 => average 2428 – average 2598, rating difference 170 Elo-points Results: 1-0 = 13.00%, ½ = 43.15%, 0-1 = 43.85% => conditioned draw rate = 62.39% (Success rate = 65.42%, Elo advantage White = 52.9 points) I implemented these findings in my program. Adantage points and draw rates are choosen randomly within in the appropriate ranges. The program will be published on Frank Qusisinsky's chess pages (I will provide the link later). I am a very amateurish programmer, the program is programmed in Basic and runs under QBX (QuickBasic)[DOS-mode!], but at least it works and provides nice results. It is able to simulate a single or double round robin for up to 8 players and is able to state the likelihood for a certain player to reach a certain rank (based on a choosen number of simulations). Best regards, Christoph Fieberg
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