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You can't compare Elo ratings over long stretches of time, period. Ratings drift over time, based on the total population of people competing. I think the most

You can't compare Elo ratings over long stretches of time, period. Ratings drift over time, based on the total population of people competing. I think the most accurate way to view Elo ratings is as a measure of skill vs. the average rated player. If you want to compare Magnus Carlsen's peak rating of 2882 in the year 2014 to Garry Kasparov's peak rating of 2851 in the year 1999, you have to know how strong the total pool of players (including all the amateurs who compete at lower levels) was in the year 2014 vs. 1999. The only way to actually anchor the Elo system over long periods of time would be to have rated humans occasionally play against a set of unchanging computer players, which could then serve as static rating calibrators. You could use those games to then calibrate Elo ratings from different time periods to a common scale, by asserting that the computer ratings don't change.

somenameforme 13d ago
Even that would be slightly malinformative because of opening theory. If you warped a very strong player from the past to the present, he'd do very poorly at first simply because of advances in opening theory. But give him a bit to catchup and he'd likely have his rating zoom on up. So modern players would do better against the static computer because of the same advantage, but that doesn't mean they're necessarily stronger in the sense that we hope to measure. The question people always want to know are things like how would a Morphy, Capablanca, or Alekhine do in modern times with access to modern theory and the like - not how well would they do against Carlsen if they went in with nothing but the knowledge of their era.
- mafuy 13d ago
  In Go, we had an extensive documentary on this, based on the strange case of a man possessed by the spirit of an ancient master Go player. I'm not going to spoil the results here; it's an enjoyable series and includes many small introductory tutorials to the game. https://en.wikipedia.org/wiki/Hikaru_no_Go https://en.wikipedia.org/wiki/Hikaru_no_Go
snakeboy 13d ago
> If you want to compare Magnus Carlsen's peak rating of 2882 in the year 2014 to Garry Kasparov's peak rating of 2851 in the year 1999, you have to know how strong the total pool of players (including all the amateurs who compete at lower levels) was in the year 2014 vs. 1999. I imagine that FIDE has all of this data somewhere, right? They don't publish more in-depth distributional analyses of players somewhere?
- DiogenesKynikos 13d ago
  The distribution of Elo ratings will not tell you how strong the average player is in an absolute sense. Elo ratings measure differences in skill between different players. A player rated 400 points above another player will win 90% of the time. Only rating differences are meaningful. Absolute ratings aren't.
  - snakeboy 13d ago
    Yes, I can understand why absolute ratings are impossible to extract. However, since the population maintains some continuity over time (players gradually enter and then leave over time), would it not be possible to reconstruct relative ratings between players that didn't play during the same era?
    - simiones 13d ago
      Only if you were to assume that a player's prowess remains constant throughout their career, which we generally know to be false. (I'm completely inventing dates here) If Fisher played Kasparov in 1990 and Kasparov played Carlsen in 2020, you can only compare Carlsen to Fisher if you assume Kasparov's skill was about the same for this entire duration, which no one believes to be the case.
      - DiogenesKynikos 12d ago
        A lot of people don't realize that chess players peak around the same age as athletes do. Carlsen was at peak dominance in his mid-20s. Kasparov peaked later, at 36 years old, but still, it wasn't at age 50 or 60. Chess requires you to be really sharp. Experience increases with age, but there's some cross-over point at which the decline in calculating speed is more important than increasing experience. Heck, I'm measurably better at chess tactics in the morning after a good night's sleep than in the evening after work.
hyperpape 13d ago
> You can't compare Elo ratings over long stretches of time, period. I agree that you cannot do it reliably, in principle. However, Bobby Fischer peaked at 2785, and Gary Kasparov peaked at 2851. These are not far from what informed observers suggest--maybe 50 or 100 points off. They are well into super-grandmaster territory. Kasparov would be 1st today, Fischer would be 4th. But on goratings.org, the top player of the 90s would be roughly 30th today. My point is that the go ratings are much more unstable than the chess ratings. With chess ratings, you'll be wrong in the details. With go ratings, you'll be catastrophically wrong.
- DiogenesKynikos 13d ago
  I agree that the drift in chess Elo ratings is slow enough that we can say Bobby Fischer at his peak would still be a strong grandmaster today (if he were given some time to study developments in opening theory). But I don't think we can say whether he would land at 2700 or 2800 in today's Elo scale.
  - hyperpape 13d ago
    This is within the realm of reasonable opinion, but I'd tentatively say it's an uncommon one--I thought it's generally agreed that the very best players of that era didn't lag contemporary players in terms of skill, only theory. I may be wrong, though.
    - DiogenesKynikos 13d ago
      Chess has developed significantly over the last 50 years. The best players now can be reasonably expected to be much more skilled than the best players of 50 years ago, even if you discount opening theory knowledge.

somenameforme 13d ago

Even that would be slightly malinformative because of opening theory. If you warped a very strong player from the past to the present, he'd do very poorly at first simply because of advances in opening theory. But give him a bit to catchup and he'd likely have his rating zoom on up. So modern players would do better against the static computer because of the same advantage, but that doesn't mean they're necessarily stronger in the sense that we hope to measure. The question people always want to know are things like how would a Morphy, Capablanca, or Alekhine do in modern times with access to modern theory and the like - not how well would they do against Carlsen if they went in with nothing but the knowledge of their era.

mafuy 13d ago
In Go, we had an extensive documentary on this, based on the strange case of a man possessed by the spirit of an ancient master Go player. I'm not going to spoil the results here; it's an enjoyable series and includes many small introductory tutorials to the game. https://en.wikipedia.org/wiki/Hikaru_no_Go https://en.wikipedia.org/wiki/Hikaru_no_Go

snakeboy 13d ago

> If you want to compare Magnus Carlsen's peak rating of 2882 in the year 2014 to Garry Kasparov's peak rating of 2851 in the year 1999, you have to know how strong the total pool of players (including all the amateurs who compete at lower levels) was in the year 2014 vs. 1999. I imagine that FIDE has all of this data somewhere, right? They don't publish more in-depth distributional analyses of players somewhere?

DiogenesKynikos 13d ago
The distribution of Elo ratings will not tell you how strong the average player is in an absolute sense. Elo ratings measure differences in skill between different players. A player rated 400 points above another player will win 90% of the time. Only rating differences are meaningful. Absolute ratings aren't.
- snakeboy 13d ago
  Yes, I can understand why absolute ratings are impossible to extract. However, since the population maintains some continuity over time (players gradually enter and then leave over time), would it not be possible to reconstruct relative ratings between players that didn't play during the same era?
  - simiones 13d ago
    Only if you were to assume that a player's prowess remains constant throughout their career, which we generally know to be false. (I'm completely inventing dates here) If Fisher played Kasparov in 1990 and Kasparov played Carlsen in 2020, you can only compare Carlsen to Fisher if you assume Kasparov's skill was about the same for this entire duration, which no one believes to be the case.
    - DiogenesKynikos 12d ago
      A lot of people don't realize that chess players peak around the same age as athletes do. Carlsen was at peak dominance in his mid-20s. Kasparov peaked later, at 36 years old, but still, it wasn't at age 50 or 60. Chess requires you to be really sharp. Experience increases with age, but there's some cross-over point at which the decline in calculating speed is more important than increasing experience. Heck, I'm measurably better at chess tactics in the morning after a good night's sleep than in the evening after work.

hyperpape 13d ago

> You can't compare Elo ratings over long stretches of time, period. I agree that you cannot do it reliably, in principle. However, Bobby Fischer peaked at 2785, and Gary Kasparov peaked at 2851. These are not far from what informed observers suggest--maybe 50 or 100 points off. They are well into super-grandmaster territory. Kasparov would be 1st today, Fischer would be 4th. But on goratings.org, the top player of the 90s would be roughly 30th today. My point is that the go ratings are much more unstable than the chess ratings. With chess ratings, you'll be wrong in the details. With go ratings, you'll be catastrophically wrong.

DiogenesKynikos 13d ago
I agree that the drift in chess Elo ratings is slow enough that we can say Bobby Fischer at his peak would still be a strong grandmaster today (if he were given some time to study developments in opening theory). But I don't think we can say whether he would land at 2700 or 2800 in today's Elo scale.
- hyperpape 13d ago
  This is within the realm of reasonable opinion, but I'd tentatively say it's an uncommon one--I thought it's generally agreed that the very best players of that era didn't lag contemporary players in terms of skill, only theory. I may be wrong, though.
  - DiogenesKynikos 13d ago
    Chess has developed significantly over the last 50 years. The best players now can be reasonably expected to be much more skilled than the best players of 50 years ago, even if you discount opening theory knowledge.