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Why isn't ELO a net zero sum?

Posted: 18 October 2023, 14:57
by detlefchef11
I just finished a 4 player game where I finished 2nd. I was the lowest rated player but nobody was rated particularly highly. Not only did I get the most points, but nobody lost any. So, the winner got 19, I got 25, and the players who tied for 3rd simply got zero. It bears mention that the player that won had the highest rating, but they were in the mid 100s, so it wasn't as if they were THAT much higher than the rest of us.

What doesn't make sense is that nobody lost anything. Well, it also doesn't make sense that I got the most points, but I was the lowest rated, so...

I used to play on * and they did have an equation that took ratings into account when awarding points, so a highly rated player would lose a lot if they lost to a low ranking one and would also gain little by beating them, but it still netted out. Mind you, they also only awarded the winner of games with 3 or more players, but that's another topic entirely. I can see both sides of that.

But, it would seem, that if there was, in fact 44 total points to be shared by the 1st place player and myself, they should come from somewhere?

ETA: Actually, the winner NOW has 119 rating having won 19 pts. So, before the game was over, they were at 100 and I was at 63. And they won, but still got less rating points than I did.

*moderator edit: please do not name other sites specifically

Re: Why isn't ELO a net zero sum?

Posted: 18 October 2023, 15:04
by Ez0ah
It is usually a net zero sum, with 2 important modifications:
- you don’t loose ELO when under 100;
- your ELO gain/loss is boosted during your first 20 games.

These modifications serve 2 purposes.
First, you can assume someone who is under 100 ELO in a specific game is still learning. Some players don’t want to include beginners at their tables, so 100 is usually the threshold to mark that you have understood the game.
Second, it helps you reach faster an ELO where you would be confortable competing with.

In your case, you haven’t played a lot of multiplayer Viticulture (with ELO activated). You were supposed to earn less ELO than the winner, but your gains were boosted, multiplied by 3 because you have played less than 10 multiplayer games.

Re: Why isn't ELO a net zero sum?

Posted: 18 October 2023, 15:19
by detlefchef11
Ez0ah wrote: 18 October 2023, 15:04 It is usually a net zero sum, with 2 important modifications:
- you don’t loose ELO when under 100;
- your ELO gain/loss is boosted during your first 20 games.

These modifications serve 2 purposes.
First, you can assume someone who is under 100 ELO in a specific game is still learning. Some players don’t want to include beginners at their tables, so 100 is usually the threshold to mark that you have understood the game.
Second, it helps you reach faster an ELO where you would be confortable competing with.

In your case, you haven’t played a lot of multiplayer Viticulture (with ELO activated). You were supposed to earn less ELO than the winner, but your gains were boosted, multiplied by 3 because you have played less than 10 multiplayer games.
Thanks so much for responding and for explaining it so well.

Re: Why isn't ELO a net zero sum?

Posted: 18 October 2023, 15:55
by Silene
Also note that when everyone starts at 0 ELO and you have a net-0 on ELO, either nobody would ever gain any elo, or you would have to go into the negative.
It is debatable that it might make more sense to start somewhere in the middle so that strong players go up and weak players go down (which BGA did until ~2016). They changed it at some point, probably for psychological reasons. It doesn't feel good to only go down too much. But to make this work, there need to be ways for points entering into the system as new players are joining (can't have net-0 because that would drag everyone down). And that is achieved by the modifications that EzOah explained above.