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How is elo calculated?

kbub
Posts: 1,377
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2/10/2014 11:26:00 AM
Posted: 2 years ago
Does anyone know exactly how elo is calculated?

For example, what if I beat someone in a debate long ago who later became a superstar. Does my elo go up as a result? (and vice-versa).
tylergraham95
Posts: 1,461
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2/10/2014 11:28:14 AM
Posted: 2 years ago
At 2/10/2014 11:26:00 AM, kbub wrote:
Does anyone know exactly how elo is calculated?

For example, what if I beat someone in a debate long ago who later became a superstar. Does my elo go up as a result? (and vice-versa).

I don't know exactly how DDO has set up its system and algorithm. That is a question for Airmax. If you want to know how ELO systems work in general, check the wikipedia article. Basically it's a number to show how good you are compared to other members, but I do not know if DDO has it set up to be retro-active.
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bladerunner060
Posts: 7,126
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2/10/2014 11:37:19 AM
Posted: 2 years ago
At 2/10/2014 11:26:00 AM, kbub wrote:
Does anyone know exactly how elo is calculated?

For example, what if I beat someone in a debate long ago who later became a superstar. Does my elo go up as a result? (and vice-versa).

I do not believe it's retroactive (after all, they may have improved after they debated you, in which case it shouldn't reflect their NEW score).

I believe it's the simple elo--just yours and theirs, at the time of debate. As others have said, though, Ore_Ele came up with it (AFAIK) and airmax would probably know for sure, being a mod.
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RoyLatham
Posts: 4,488
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2/10/2014 12:51:21 PM
Posted: 2 years ago
Basically the Wikipedia formula http://en.wikipedia.org... is used, but with a 50 point bonus given to the instigator or the debate.

The formula should use the Elo scores are the start of the debate, but as best I can deduce the formula actually uses the Elo scores at the end of the debate, when voting closes. I've asked several times and never gotten an answer. But in either case, history after the voting ends doesn't count -- as far as I can tell.

In the early days of DDO, the default was that voting never ends. Elo counts whoever is ahead at any time as the winner, and it seems to be using the current Elo of opponents. As a result, the fluctuations in Elo ratings due to open old debates is substantial. I've noticed that some, but apparently not all, of the old debates have been closed to voting. I like to make a deal of it, but it's not really that important. I'm told it's too much work to fix.
bsh1
Posts: 27,503
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2/10/2014 1:45:13 PM
Posted: 2 years ago
At 2/10/2014 12:51:21 PM, RoyLatham wrote:
Basically the Wikipedia formula http://en.wikipedia.org... is used, but with a 50 point bonus given to the instigator or the debate.

I thought it was a 25 point bonus to the instigator...?
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RoyLatham
Posts: 4,488
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2/10/2014 1:56:59 PM
Posted: 2 years ago
At 2/10/2014 1:45:13 PM, bsh1 wrote:
At 2/10/2014 12:51:21 PM, RoyLatham wrote:
Basically the Wikipedia formula http://en.wikipedia.org... is used, but with a 50 point bonus given to the instigator or the debate.

I thought it was a 25 point bonus to the instigator...?

Yes, you are right it's 25 points.

W = winner's original ELO
L = loser's original ELO
D = change in ELO

D = 100*(W+9L)/10W

And there is a 25 point instigator advantage (meaning the instigator gets +25 and the contender gets -25).

This thread points to data inconsistent with the way the calculations are supposed to be done: http://www.debate.org...