Make ELO more stable (show mean over last ~100 games)

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Joined: 23 October 2013, 17:50

Make ELO more stable (show mean over last ~100 games)

Post by Silene » 16 May 2019, 10:40

I feel like ELO is going up and down a lot. If I have a winning/losing-streak, ELO is sometimes going up/down by a lot more than 100 points. I think that's not good, because
  1. my skill didn't change that much (if at all) and
  2. my opponents gain more/less ELO by playing against me depending on wether they play me after a good/bad streak - which is not fair to them because my skill (and therefore the difficulty to beat me) is the same for them no matter when they play me
I think it would be good to have an ELO-curve that is more "smooth" around the real value (that represents my real strength)
Compare to how it's done on this site (no board-games but it doesn't matter): ... /index.php
--> click any name to show their rank-graph
Black line: shows rating from day-to-day
Green line: shows mean over black line in last 50 days
Red line: shows mean over black line in last 200 days

ELO on BGA right now is very similar to the Black line
But I think it would be great to show the player's level similar to the red line

How to do it
  • Calculate "daily-ELO" as-is (same formula).
  • In Addition calculate "real-ELO" as mean over daily-ELO after the last 100 games (or another amount - maybe depending on number of games played by the player)
  • After a game, compare my "daily-ELO" with my opponents "real-ELO" to calculate my new "daily-ELO"
  • and compare THEIR "daily-ELO" with my "real-ELO" to calculate their new "daily-ELO"
  • for most purposes show "real-ELO" (on profile-page, on game-tables before joining,...). In statistics show both (i.e. on calculation after the game show what you gained in "daily-ELO" - "real-ELO" is not gonna change much anyway (which is good)
  • Fair ELO-change to the opponent (depends on real strength and not on a random previous win/loss-streak)
  • Almost impossible to reach an unrealistic maximum point by a lucky random walk.
  • Not much point in settleing on a good ELO because a single game doesn't change that much.
  • More complicate for the site (and to implement) and maybe confusing for new players
  • Needs a bunch of games to settle while not yet around real strength. (Maybe it would be good to exclude first ~100 games from real-ELO-calculation or take fewer games into account until you're somewhat settled around a realistic value)

I know there are other threads about ranking and leaderboard. This is about ELO as a measurement of skill - no matter when you played. Please don't write about ranking-list here. I think those should be separated (i.e. RANK could be calculated by ELO modified by recent activity or so but that's not what this thread is about)

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Joined: 14 November 2011, 22:40

Re: Make ELO more stable (show mean over last ~100 games)

Post by latexrhombus » 14 June 2019, 17:04

I think the easiest way to "stabilize" ELO would be to lock in a player's highest reached ELO for a particular game.

It has to be understood that ELO and similar systems are designed to rank players in games containing no random elements, i.e. chess and go. Understanding this, the ELO system on this website will never be perfect and, in general, seems to function as intended.

The issue with ELO is that top players will not continue to play because they care about BGA prestige. The simplest solution to this (which would encourage play and help the website remain active across a wider array of games) would be to separate current ELO and highest ELO reached for each player in each game.

Prestige points such as "top player" can still be awarded based on highest ELO reached, but they will have a functional ELO rating that fluctuates up and down based on play. This would encourage play as win and loss streaks are common in games with high levels of randomness so active players would tend to shift up in the rankings.

I doubt many people will read this or it will ever be implemented, but I think it would take steps to address a well-known issue on this site and would not represent a major change.

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Joined: 24 November 2013, 00:02

Re: Make ELO more stable (show mean over last ~100 games)

Post by asd123321 » 18 June 2019, 00:51

ELO is too much affected by the last 20 games or so. What is needed is a factor that would be applied that the more games you play the less the ELO changes. They only do it up to a certain number.

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