about the ELO points gained or lost at the end of a game

[marieroussel]

Hello all,

I'm wondering how the ELO point you gain or loose at the end of a game are counted. Sometimes, I play against people with way less ELO than me so I gain around 3 ELO and they loose about the same. But sometimes I gain 3 ELO and they loose 8 or 11... Sometimes it's the other way round (I loose some ELO and they gain way more than what I lost). I don't really get it. Does someone have any idea about the scoring or any idea about where to find the information?

[Meeplelowda]

Hello all,

I'm wondering how the ELO point you gain or loose at the end of a game are counted. Sometimes, I play against people with way less ELO than me so I gain around 3 ELO and they loose about the same. But sometimes I gain 3 ELO and they loose 8 or 11... Sometimes it's the other way round (I loose some ELO and they gain way more than what I lost). I don't really get it. Does someone have any idea about the scoring or any idea about where to find the information?

There are many factors at work: 1) the rating of the people you're losing to, 2) how many times you've played the game, 3) how many people you're playing against, 4) whether you're under 100 Elo, and 5) whether you're barely above 100 Elo.

In case you haven't read the related FAQs, here are the links:
How does the ELO change calculation work?
How is my ELO updated?

Unfortunately, in a revision to the FAQ they removed the explanation of how the K-factor works on BGA. The FAQ used to explain that:

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 11th and 20th games, 20 for your 21st onwards.

The K-factor is a linear scaling factor in the Elo calculation, so a person with a K-factor of 60 will gain (or lose) three times as many points as someone with the same rating who is playing a game for the 21st+ time, all other things being equal. There is also some question of whether friendly games count in the number of times played, which I don't recall off the top of my head.

And see this thread for a discussion for how Elo in multi-player games is awarded, which not a simple as adding up all the Elo adjustments that would have been made in a 1 v 1 match against all the other players: https://boardgamearena.com/forum/viewtopic.php?t=46254

Also, if you're under 100 Elo, you can't lose points. If you're above 100 Elo, you can't fall below 100 even if the calculation says you should lose more points.

[Ceaseless]

Hello all,

I'm wondering how the ELO point you gain or loose at the end of a game are counted. Sometimes, I play against people with way less ELO than me so I gain around 3 ELO and they loose about the same. But sometimes I gain 3 ELO and they loose 8 or 11... Sometimes it's the other way round (I loose some ELO and they gain way more than what I lost). I don't really get it. Does someone have any idea about the scoring or any idea about where to find the information?

https://boardgamearena.com/faq?anchor=f ... oisupdated How does the ELO change calculation work?

The ELO calculation is based on the concept of high risk, high reward: defeating a stronger player (high risk) significantly boosts your rating (high reward). Conversely, losing to a weaker player substantially decreases it.

While you can find general information about the Elo formula online, be aware that Board Game Arena incorporates its own modifications. Primarily these are reflected in modifiers that together determine the magnitude of the ELO change (called the K-factor in the standard Elo formula):

Game Experience: players with fewer games played on BGA have a higher ELO adjustment to facilitate reaching the appropriate level within the ranking system.
Consecutive wins: beating the same player repeatedly makes the outcome less outstanding.

ELO can never be lost before reaching a score of 100 and can never drop below this threshold once it has been reached.

A few reasons why the players aren't matching in a +x/-X fashion. I'm betting on the higher k factor for newer Splendor Duel players being what throws you off. After all, a new account isn't properly rated, so BGA is accelerating their early changes to get them to their proper rating faster. After those early games, they slow it down now that they have a rough idea. Meeple already posted some numbers, so you'll see k factors leading to two or three times the change. The basic view only shows integers even though BGA calculates deeper than that, so numbers can look a bit off give or take 1 point, though if you view the rating changes on recent enough games they'll show visibility to the nearest hundredth, so things might only look off give or take 0.01 points.

https://boardgamearena.com/table?table=918024729 Your opponent's 19th rated game of Splendor Duel. So they lost two times as much as you gained. +3.42 vs -6.85

https://boardgamearena.com/table?table=919242780 Your opponent's 5th rated game of Splendor Duel. So they lost three times as much as you gained. +2.82 vs -8.45

https://boardgamearena.com/table?table=914426089 Your opponent's 13th rated game of Splendor Duel. So they lost two times as much as you gained. +2.85 vs -5.71

[marieroussel]

Thanks for your answers. Yes, it was probably the k-factor that I didn't know existed but that explains a lot!

Thanks again and happy gaming!

Marie