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by franknstein
1400 days ago
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Magnus Carlsen: 2864 Elo Stockfish: 3585 Elo "Elo suggested scaling ratings so that a difference of 200 rating points in chess would mean that the stronger player has an expected score (which basically is an expected average score) of approximately 0.75, and the USCF initially aimed for an average club player to have a rating of 1500." I guess that means that Magnus has expected score of roughly 0.25^((3585 - 2864)/200) = 0.00675 against Stockfish 15, which is basically 1 in 200 games? |
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Instead, you should convert the 0.25 to "odds" form. 0.25 is 1:3 odds, represented by the number 1/3. (1/3)^((3585 - 2864)/200) is about 0.01905 (still in odds form). To convert this back to an expected score you would take 0.01905 / (1 + 0.01905) = 0.0187. So Magnus Carlsen's expected score is 0.0187.
Applying the same method to Stockfish, we have 3:1 odds, which is represented by the number 3. 3^((3585 - 2864)/200) is about 52.48. Converting back to expected score we get 52.48 / (1 + 52.48) = 0.9813. So Stockfish's expected score is 0.9813.
Our sanity check is to add 0.0187 + 0.9813. The result is 1.0, as it should be.