Calcul point in equality

[Manassès I]

Hello,
when 2 players make perfect equality, the player with the most Elo points lose point, the other play win,
how is it calculed ?

[Jest Phulin]

Fromm the FAQ

The easiest situation is a 2 player game. You will gain a number of ELO points equal to K x (W - p(D)) where:

• W is the result of the game: 1 for a victory, 0 for a defeat, 0.5 for a tie.
• D is the difference of ELO between you and your opponent.
• p(D) is the probability of victory considering the previous difference (see Wikipedia for details).
• K, the 'elasticity factor,' has a value that depends on the number of games you have played: 60 for your first 10 games, 40 between your 10th and 20th games, 20 for your 21st onwards.

So, the big point is that W changes to 0.5 for a tie, instead of being 1 for a win and 0 for a loss.

And, for those wondering why there is an ELO shift in a tie (why someone with a higher ELO should actually lose points for not losing the game)... The two players played the same, their ELOs should move closer to each other. The higher ELO player loses some points, the lower player gains some points.

[Manassès I]

thx you very much !

[Wojtek_bob]

Hi!

I was struggling with similar issue some time ago with a Connect Four game. I'll repost the message from Connect Four dedicated forum (https://boardgamearena.com/forum/viewto ... 46&t=18454) as I haven't received a clear explanation yet (only confirmation that there is something wrong):

I have a question about drawn games and Elo rating change. Some time ago, I played a game that ended in a draw (https://boardgamearena.com/table?table=123567040). According to the info from the result section: "the winning percetange for a player is 80% (or 20%), which results in the Elo change of -+6.09". However, our ratings remained unchanged.

As I'm a relatively new user here, I'm not really sure how the draws are treated in this particular game, but anyway, there is contradictory information in the result section then. I've reported it as a bug (https://boardgamearena.com/bug?id=28098) but I doubt whether it would be reviewed anytime soon unless it's upvoted.

Can someone explain why it is so?