Given the issues with rating people who mostly play within a cluster that contains few people who play outside the cluster, I was expecting rating systems to take more notice of results against another player who was well connected to many different clusters of players. Yet they seem not to. What am I missing in my understanding?

  • I would guess that this hasn't been a main focus because in many scenarios that is unlikely to happen. However, there would be some uses cases of course, so it might be interesting to try and model it.
    – koedem
    Commented Feb 3, 2022 at 4:04
  • 1
    tl;dr They cope badly
    – Evargalo
    Commented Feb 3, 2022 at 7:10
  • @koedem I think the US creates problem for international rating systems by most mid range US players not playing in a international rated match until they have become very experienced players. There is also issues that is clearly easyer to get 2500 in some countries then others. Commented Feb 3, 2022 at 11:25

1 Answer 1


Your understanding is correct, at least for the Elo system (and systems derived from it). These systems only make adjustments to a player's rating based on results against other players that they've actually played against. They don't make any explicit attempt to extrapolate a player's performance based on how that player's performance compares against other players that their opponents have played (but whom the player under consideration has not played).

You can find a description of the US Chess rating system here, which describes the computations that are done to adjust a player's rating after an event in which they've played.

  • I was thinking "K" could be higher when playing someone with a low level of connection between the players. Commented Feb 2, 2022 at 20:30
  • One could potentially try to atone for a multitude of sins via the K factor. As used in Elo-like systems, though, it's strictly a measure of how volatile a player's rating is, and only information about that player is used to choose K. The general assumption is that the ratings of low-rated players may change quickly, but that that high-rated players probably won't get worse (or much better) quickly. It's further assumed ratings based on a small number of games may change quickly (the rating system doesn't know much about the player yet), while long-established ratings are more stable.
    – patbarron
    Commented Feb 2, 2022 at 21:04
  • There is already a system in US when new people who do a lot better then expected get their rating increaed more. Maybe also a bonus when doing a lot better then expected agaist playing who are not well connected to you but are well connected to many other players. Commented Feb 2, 2022 at 21:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.