Answers.Body: <p>As above in the comments, it is impossible to estimate the rating based on a single game only. The reasons for this are:</p>
  
  <ul>
  <li><p>The rating number itself is <em>statistical and relative</em>, i.e. it tells you something about the level relative to other players. Basically if you play against players of the same rating 1000 games, you would score half the points. Of course each individual game could be a win for either player or a draw.</p></li>
  <li><p>Playing strength and therefore rating depends on many factors (e.g. tactics, positional/strategy/...., playing style: active/passive....). Also you might very well have situations where a lower rated player is scoring particularly well against a higher rated player because their relative playing styles are such that it favors one player.</p></li>
  </ul>
  
  <p>That being said, based on the game, I note that black has weak positional understanding (creating too many weak squares, blocking his own pieces....) and is not aware of general principles like develop pieces, don't make too many pawn moves... All of this is typical for a beginner player rated around 1000. </p>
  
  <p>The white player was playing much more normally, developing pieces, occupying the center, castling, etc.</p>
  
  <p>As a positive note, neither player did an <em>easy</em> piece blunder. Black blundered mate in 1 with 22...Nxb2, but might have thought that he could recapture on c6 which he cannot because of the pin. White probably did not calculate the consequences of 22...Nb8 (which was not played) when the position is not all that simple (but of course still winning for white). Not blundering pieces is not typical of a 1000 rated player.</p>
  
  <p>Given that the lichess ratings are based on hundreds of games, I would trust them to some extent. Of course these ratings only tell you the relative strength among players on lichess and can not be converted to FIDE ratings (which describe the relative strength with respect to FIDE rated players). When attempting to convert I'd give them an error margin of plus minus 200 points or so.</p>
  
  <p>So all in all, I'd estimated these players to be between 900 and 1300 for black and between 1200 and 1600 for white, but as mentioned this is very rough.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-02-22T18:28:59.583Z
Answers.LastActivityDate: 2018-02-22T18:28:59.583Z
Answers.UserDisplayName: user1583209
Body: <pre><code>[Event "Rated Rapid game"]
  [Site "https://lichess.org/PuymBQf1"]
  [Date "2018.02.22"]
  [Round "-"]
  [White "chess_lover_2001"]
  [Black "potema"]
  [Result "1-0"]
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  [UTCDate "2018.02.22"]
  [UTCTime "14:38:35"]
  [WhiteElo "1133"]
  [BlackElo "1390"]
  [WhiteRatingDiff "+21"]
  [BlackRatingDiff "-19"]
  [Variant "Standard"]
  [TimeControl "900+3"]
  [ECO "B00"]
  [Opening "St. George Defense"]
  [Termination "Normal"]
  [Annotator "lichess.org"]
  
  1. e4 a6 { B00 St. George Defense } 2. d4 b5 3. c4 c6 4. b4 e6 5. c5 Bb7 6. e5 Ne7 7. Nc3 a5 8. Bd3 axb4 9. Ne4 Nd5 10. Nf3 h6 11. Bb2 Qa5 12. O-O g5 13. Nd6+ Bxd6 14. exd6 f5 15. Ne5 Na6 16. Qh5+ Kd8 17. Nf7+ Kc8 18. Nxh8 Kb8 19. Qe8+ Ka7 20. Qxd7 Nf4 21. Nf7 Nxd3 22. Ne5 Nxb2 23. Nxc6# { White wins by checkmate. } 1-0
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-02-22T15:14:39.100Z
Comments.Text: It's not feasible to determine the Elo strength of two players based on one game only. But then again, in the game info we see that white's rating is 1133 and black's rating is 1390. Combine this with the info that this game seems to have been played on the lichess server, and these numbers could possibly be used to get some (rough) estimate of Elo strength, although it's difficult to compare normal Elo to lichess Elo.
Comments.UserDisplayName: Scounged
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-02-22T15:17:45.683Z
Comments.Text: The white isn't accurate to to unconventional circumstances so that's why I asked. Blacks reply to e4 seemed odd.
Comments.UserDisplayName: Evin Switzer
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-02-23T16:00:13.363Z
Comments.Text: very weak opening. Lichess, in my opinion, tends to over rate early on. probably below 1200
Comments.UserDisplayName: TheAutomaton
Tags: <analysis>
Title: What would be the estimate of the ratings of white and black in this game? Keep in mind, it's a rapid game
ThreadText: # What would be the estimate of the ratings of white and black in this game? Keep in mind, it's a rapid game
  
  (Asked by: username_0 on 2018-02-22)
  
  [Event "Rated Rapid game"]
  [Site "https://lichess.org/PuymBQf1"]
  [Date "2018.02.22"]
  [Round "-"]
  [White "chess_lover_2001"]
  [Black "potema"]
  [Result "1-0"]
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  [UTCDate "2018.02.22"]
  [UTCTime "14:38:35"]
  [WhiteElo "1133"]
  [BlackElo "1390"]
  [WhiteRatingDiff "+21"]
  [BlackRatingDiff "-19"]
  [Variant "Standard"]
  [TimeControl "900+3"]
  [ECO "B00"]
  [Opening "St. George Defense"]
  [Termination "Normal"]
  [Annotator "lichess.org"]
  
  1. e4 a6 { B00 St. George Defense } 2. d4 b5 3. c4 c6 4. b4 e6 5. c5 Bb7 6. e5 Ne7 7. Nc3 a5 8. Bd3 axb4 9. Ne4 Nd5 10. Nf3 h6 11. Bb2 Qa5 12. O-O g5 13. Nd6+ Bxd6 14. exd6 f5 15. Ne5 Na6 16. Qh5+ Kd8 17. Nf7+ Kc8 18. Nxh8 Kb8 19. Qe8+ Ka7 20. Qxd7 Nf4 21. Nf7 Nxd3 22. Ne5 Nxb2 23. Nxc6# { White wins by checkmate. } 1-0
  
  **Tags:** analysis
  
  > **Comments:**
  > **username_1**: It's not feasible to determine the Elo strength of two players based on one game only. But then again, in the game info we see that white's rating is 1133 and black's rating is 1390. Combine this with the info that this game seems to have been played on the lichess server, and these numbers could possibly be used to get some (rough) estimate of Elo strength, although it's difficult to compare normal Elo to lichess Elo.  
  > **username_0**: The white isn't accurate to to unconventional circumstances so that's why I asked. Blacks reply to e4 seemed odd.  
  > **username_2**: very weak opening. Lichess, in my opinion, tends to over rate early on. probably below 1200  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_3 on 2018-02-22. Score: 3
  
  As above in the comments, it is impossible to estimate the rating based on a single game only. The reasons for this are:
  
  * The rating number itself is *statistical and relative*, i.e. it tells you something about the level relative to other players. Basically if you play against players of the same rating 1000 games, you would score half the points. Of course each individual game could be a win for either player or a draw.
  * Playing strength and therefore rating depends on many factors (e.g. tactics, positional/strategy/...., playing style: active/passive....). Also you might very well have situations where a lower rated player is scoring particularly well against a higher rated player because their relative playing styles are such that it favors one player.
  
  That being said, based on the game, I note that black has weak positional understanding (creating too many weak squares, blocking his own pieces....) and is not aware of general principles like develop pieces, don't make too many pawn moves... All of this is typical for a beginner player rated around 1000.
  
  The white player was playing much more normally, developing pieces, occupying the center, castling, etc.
  
  As a positive note, neither player did an *easy* piece blunder. Black blundered mate in 1 with 22...Nxb2, but might have thought that he could recapture on c6 which he cannot because of the pin. White probably did not calculate the consequences of 22...Nb8 (which was not played) when the position is not all that simple (but of course still winning for white). Not blundering pieces is not typical of a 1000 rated player.
  
  Given that the lichess ratings are based on hundreds of games, I would trust them to some extent. Of course these ratings only tell you the relative strength among players on lichess and can not be converted to FIDE ratings (which describe the relative strength with respect to FIDE rated players). When attempting to convert I'd give them an error margin of plus minus 200 points or so.
  
  So all in all, I'd estimated these players to be between 900 and 1300 for black and between 1200 and 1600 for white, but as mentioned this is very rough.
  
  
  ---
  
  