Author Topic: Elo ratings  (Read 18445 times)

Offline Jéré

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Elo ratings
« on: January 30, 2017, 09:01:12 AM »
I've often been asked what is this strange Elo thing. I think it's important to write a few lines about this since it is used for all online competitions held on Carcassonne Central. This thread is an attempt to make it clearer.

What is the Elo rating?

It's a method used to calculate your relative skill level in 1vs1 matches. It was originally used for Chess but it is also applicable to other games, like Carcassonne!

How does it work?

Before you play your very first game, your score is set to 1200 and this score goes up and down as you win or lose matches. How many points you win or lose depends on the score of your opponent. Basically, the strongest your opponent (compared to you), the more points you get if you win. You can get a big reward for winning against all odds a match versus an opponent that is considered much stronger than you, but beware, losing against a player that has a much lower score can have the opposite effect! Interestingly, you won't lose too many points if you lose against a strong opponent... because Elo predicted you'd lose! That's right, Elo ratings are used to predict the outcome of a specific match. By comparing the Elo ratings of 2 players, you can tell who's going to win... but that's theory of course!

Unfortunately, it would be too much work to publish the Elo variations after every single game played at Carcassonne Central. Therefore, it was decided to publish the Elo ratings only after competition milestones. But if you are curious about your current score before its publication, don't hesitate to ask. Send me a PM! Also my spreadsheet is available upon request.

What about ties?

If you tie a game with stronger player, you will get points and he/she will lose a few! Simply because it goes against the predicted outcome: Stronger player should win.

Self-correcting system? What is this?

Imagine a big elastic rubber band, that's the Elo system. Say you're on a losing streak and your score gets too low, eventually you'll bounce back (be patient it can take time), prove Elo wrong and gain rating points until your rating better reflects your playing skill value. In the same vein, being the top-ranked player is not the most comfortable position, as all other players have lower scores and any loss could hurt your rating badly. In other words, top-ranked player must keep winning which becomes increasingly difficult! The same elastic rubber band that helps you to bounce back can also bring you down!

Want to know more?

There is a wikipedia page here with way too much detail. :)

See below the Elo ratings that were published after each major competition. New rankings will be published also in this thread for easy reference. Comments/Suggestions are very welcome!

Basegame League 2014
World Cup 2014 
T&B League 2015 
I&C League 2015
A&M League 2015 
World Cup 2015 
P&D League 2016 
Tower League 2016 
World Cup 2016

Current ranking (as of May 11th, 2018):



Linkback: http://www.carcassonnecentral.com/community/index.php?topic=3129.0
« Last Edit: May 11, 2018, 12:32:12 AM by Jéré »

Offline danisthirty

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Re: Elo ratings
« Reply #1 on: January 30, 2017, 09:34:12 AM »
Say you're on a losing streak and your score gets too low, eventually you'll bounce back (be patient it can take time)...

I'm trying! :o

Many thanks for this great post Jéré, it was a very interesting read! Funny how I almost got to the top of the Elo ladder after doing well in the 2015 World Cup and then the Princess & Dragon league, but seem to be in free fall at the moment!
« Last Edit: January 30, 2017, 09:37:56 AM by danisthirty »

Offline Leven

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Re: Elo ratings
« Reply #2 on: January 30, 2017, 10:47:40 AM »
This one is missing from the list:
A&M League 2015

Offline Jéré

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Re: Elo ratings
« Reply #3 on: January 30, 2017, 12:35:32 PM »
This one is missing from the list:
A&M League 2015

Ups! Fixed! Thanks!

Offline Jéré

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Re: Elo ratings
« Reply #4 on: February 01, 2017, 11:26:13 PM »
Update: Feb 2nd 2017


Offline Jéré

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Elo ratings
« Reply #5 on: February 13, 2017, 12:38:39 PM »
Update: Feb 13th 2017


Offline danisthirty

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Re: Elo ratings
« Reply #6 on: February 13, 2017, 03:46:57 PM »
Thanks for your tireless efforts keeping these up to date Jéré. :(y)

I have a question though: a friend of mine, lets call him IanisFifty, is obsessed with this game called Barkassonne (it's a bit like Carcassonne but with dogs) and is an admin at www.barkassonnecentral.com where he takes place in the occasional tournament against other members of the community there. Anyway, although he likes to pretend that he's actually pretty good, his Elo rating has been falling steadily over recent competitions and he just wondered what would happen if/ when it reaches 0? Is it possible for it to go below 0? He really wants to know... :'(

Offline Jéré

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Re: Elo ratings
« Reply #7 on: February 28, 2017, 09:01:46 AM »
Thanks for your tireless efforts keeping these up to date Jéré. :(y)

I have a question though: a friend of mine, lets call him IanisFifty, is obsessed with this game called Barkassonne (it's a bit like Carcassonne but with dogs) and is an admin at www.barkassonnecentral.com where he takes place in the occasional tournament against other members of the community there. Anyway, although he likes to pretend that he's actually pretty good, his Elo rating has been falling steadily over recent competitions and he just wondered what would happen if/ when it reaches 0? Is it possible for it to go below 0? He really wants to know... :'(

Say that we start again with an Elo rating of 1200 and we play each other like there is no tomorrow and in the process I give you the greatest Carcassonne lesson in the history.... well, after losing 157 games in a row, you'd reach an Elo of 845, and beyond that you wouldn't lose any more points playing against me because the gap would be too great (eg. 1555 vs 845). I wouldn't gain, you wouldn't lose anymore. You'd have to keep losing against other extremely low rated players. The bottom line is that even if you really try to lose, it is quite unlikely to happen, and would take forever...

Offline danisthirty

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Re: Elo ratings
« Reply #8 on: February 28, 2017, 09:41:29 AM »
Thanks Jéré, I'll let IanisFifty know... :) :(y)

Offline Jéré

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Elo ratings
« Reply #9 on: March 01, 2017, 01:44:12 PM »
Update: March 1st 2017

(Removed by Jéré, see March 4th update)
« Last Edit: March 04, 2017, 05:41:21 AM by Jéré »

Offline Leven

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Re: Elo ratings
« Reply #10 on: March 01, 2017, 02:55:38 PM »
Jéré, shouldn't this update include results of the BCB expansion league? It apparently doesn't.
E.g. you lost a game before our basegame league match in the BCB league so your initial rating should be lower than it was after the 2nd round of the basegame league. If I'm not mistaken than the order of the games is significant in terms of calculating Elo.
« Last Edit: March 01, 2017, 02:57:31 PM by Leven »

Offline Jéré

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Re: Elo ratings
« Reply #11 on: March 02, 2017, 01:27:38 AM »
Jéré, shouldn't this update include results of the BCB expansion league? It apparently doesn't.
E.g. you lost a game before our basegame league match in the BCB league so your initial rating should be lower than it was after the 2nd round of the basegame league. If I'm not mistaken than the order of the games is significant in terms of calculating Elo.

Excellent question Leven! And not so easy to answer...

There are good reasons why I did that, and there are also good reasons why I shouldn't have done that...

It is actually quite a luxury to have an Elo update every 2 weeks. The format of the basegame league is easy to follow and record so I opted for what was more convenient for me. It gets more complex if I need to monitor 4 threads and look at the all the timestamps of the posts to figure out the chronological order. I'm afraid to lose my sanity while doing that... it seems that I would need to read all competition threads on a daily basis not to lose track. My idea was to append the BC&B league results to the Basegame league results after the group stages are completed. I actually did not even start to record the BC&B league results! When I do, I usually start scanning a thread from page 1 until the end and write down all the scores.

Believe me, as a perfectionist, I am really annoyed by this... at the moment, I chose convenience over accuracy but I am seriously considering fixing this. I would need to update my Excel spreadsheet to add a column to track the date and time of each game and start entering the results after each game, and not by block of competition like it is now.

A disadvantage of doing that is also that the Elo updates will be less meaningful. I mean that, right now, it is pretty clear how well you are doing compared to others because everybody has played an equal number of games after a complete round. If I would include partial results of the BC&B league, these clear results are diluted and mixed other incomplete results... which gives something not really pleasant to look at or try to understand. I guess it would be up to the indivudual players to keep in mind how many games they have played since the last update... or I could perhaps list all the games that are included in each update, but again, this could be a LOT of work. I have fun doing this but if one day it becomes too tedious I might lose interest, hence the reason to keep the balance.

I am really struggling with the idea of mixing the results of two different competitions. Did you also noticed that I use a different cell colour to indicate who's in and who's out (non-participants are greyed out)? That info would be lost also. I'll have to put more thoughts into this. The fact that the Basegame league spans over a long period of time pretty much answers the question: I can no longer delay the publication of the results of the BC&B league! I might cancel the last uptade and start over to insert the BC&B league results in such way that the chronological order is honoured.

My sincere apologies for the confusion!


Offline thodekey

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Re: Elo ratings
« Reply #12 on: March 02, 2017, 02:17:01 AM »
Just a thought, Jéré:

As a -yet not that good- table tennis player in an official competition, i have a ELO-ranking for that sport.  All the participating players can watch their ELO-points, results and statistics online all of the time.  All every club in that league has to do, is charging their own results in the system and ELO-points are automatically recalculated.  Even when there is a tournament and those results are charged later than other later results, the date of the game is taken in notice so the ELO-ranking is all of the time updated and recalculated.  To exclude 'fraude' with the results, the opponent of the player/club who gave in the results in the system, has to confirm those results.
An exemple of my not so marvellous season, for the moment:

http://competitie.vttl.be/?menu=6&sel=31902&result=1&category=1

Pretty sure you'll understand the language in the link, given the fact we speak the same language - yet, in a totally different way. :-)

For the record: i'm not suggesting to make the same kind of platform yourself - that would be way too time-consuming and keep you away of the real deal: playing Carcassonne - but I wonder if there isn't a platform online somewhere that we could use.  In that way, results and ELO-rankings would always be up to date.
And if there is a way the participants to the league games can give in themselves the results of the games online, that would decrease your work a lot - which is much appreciated by the way.

Maybe this is a helpful link?
https://www.quora.com/Is-there-free-Elo-rating-system-software

Groeten,
Thodekey

Offline Jéré

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Elo ratings
« Reply #13 on: March 04, 2017, 05:41:45 AM »
Update: March 4th 2017

This update takes into account all games played in the Round 3 of the Basegame league, 14 games played in the BC&B league and well as the first 2 games played in the Round 4 of the Basegame league.

« Last Edit: March 04, 2017, 05:52:17 AM by Jéré »

Offline Jéré

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Re: Elo ratings
« Reply #14 on: March 04, 2017, 05:50:00 AM »
Just a thought, Jéré:

As a -yet not that good- table tennis player in an official competition, i have a ELO-ranking for that sport.  All the participating players can watch their ELO-points, results and statistics online all of the time.  All every club in that league has to do, is charging their own results in the system and ELO-points are automatically recalculated.  Even when there is a tournament and those results are charged later than other later results, the date of the game is taken in notice so the ELO-ranking is all of the time updated and recalculated.  To exclude 'fraude' with the results, the opponent of the player/club who gave in the results in the system, has to confirm those results.
An exemple of my not so marvellous season, for the moment:

http://competitie.vttl.be/?menu=6&sel=31902&result=1&category=1

Pretty sure you'll understand the language in the link, given the fact we speak the same language - yet, in a totally different way. :-)

For the record: i'm not suggesting to make the same kind of platform yourself - that would be way too time-consuming and keep you away of the real deal: playing Carcassonne - but I wonder if there isn't a platform online somewhere that we could use.  In that way, results and ELO-rankings would always be up to date.
And if there is a way the participants to the league games can give in themselves the results of the games online, that would decrease your work a lot - which is much appreciated by the way.

Maybe this is a helpful link?
https://www.quora.com/Is-there-free-Elo-rating-system-software

Groeten,
Thodekey

Thanks for your input Thodekey. Also for the links! I am indeed considering finding a better way to record Elo ratings, some sort of program or webpage could certainly help. Will continue to look at options.

For now, I managed to recalculate and publish a new update. I had to go through all competition threads and record as well the moment games were played. Sometimes I had to go back and forth to figure out the right order (for instance Adrornalin has played 3 games in a single evening in different leagues, and there are other examples like this). It took me a bit more than 2 hours.


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