New ELO

[sourisdudesert]

New: the ELO rating system used in Board Game Arena has been refined. Until now, BGA ELO rating system was "inspired by the real ELO formula". Now, it is the real ELO formula, the one used for chess players.

The practical consequences:

• ELO ratings vary more slowly. You gain less points when you win, and loose less points when you loose.
• ELO ratings vary more for new players: during your 30 first games, your ELO rating vary more than after. Thus, ELO rating of new players tend to be quickly adjusted to their real level.
• If the difference between your ELO and an opponent's ELO is greater than 400, the system consider that the difference is 400. Thus, Masters shouldn't be afraid to play (and eventually, to loose) against low-rated players.

Note: the 2 last rules are used by World Chess Federation.

Another change: when a player is leaving a game in progress, he looses the same number of ELO points as if he would loose this game (ie: last place). There is no more "fixed 30 points penalty". Note that sore looser should rather play the game until the end to avoid the "leave" mark on their profiles.

Cheers,

[SonGoku]

interesting idea,but how could i be in some game so high like Paolo,first player,who scored 3000+ ELO? maybe new elo system sounds like good idea,but u didnt think out with our ELO scores enough.

[Cabigon]

It sounds interesting. But I am still not fully understood.
1. Would earning 0 ELO happened?
2. Any examples on different cases?

Remarks: Need to change something in "Help"--> "rating" ?

[yaron]

Thanks for the information!

A few comments:

1. With the new system, all the ratings will be lower. For example, under the old formula, if you beat someone 90% of the time, your rating would be 752 higher than theirs. With the new formula, It will be only 366 higher. So the highest rating for RftG (for example) will now be around ~2100 instead of ~2700, etc.
This is not a problem in itself, of course. We'll just have less Masters and Experts. However, some players already have very high ratings, achieved under the old system. If they keep playing, their scores will rapidly fall to the new level. If they are no longer active, it will now be impossible for new players to get anywhere near their ratings.
You can solve this by recalculating everyone's ELO again using the new system (if you have the logs) - so that all scores are re-calibrated to the new system.
2. The 400 point rule can be easily abused by strong players who only play against very weak players. They never lose, but still get almost 1.5 rating points per game - with no risk. In professional chess, it is impossible to abuse the system in this way, because players do not select their opponents (each tournament is only open for players within a certain range).
3. FIDE has taken a lot of criticism for using low K's (15 and 10). See, for example: http://www.chessbase.com/newsdetail.asp?newsid=562. It seems that with such a low K, players improve faster than the system can change their ratings (even after the first 30 games). Most other organisations use K's between 24 and 32.
4. Could you please tell us the formula used for multi-player games?

Thanks!
Yaron

[zfm]

+1 to yaron's first comment. If someone has already had very high ELO, it's almost impossible for new player to get anywhere around it... Recalculate everything, reset the score (which is totally bad idea), or back to the old system.

[oren]

zfm right.

[sourisdudesert]

The discussion continue there, with new elements

(topic closed)