WTA Elo Ratings - revised (04/11/2013) - TennisForum.com
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 Dec 1st, 2012, 08:54 PM #2 amirbachar Senior Member   Join Date: Apr 2006 Posts: 241 Re: Elo-Ratings How did you choose the K-factor? The one that gives the best predictability to the rankings?
Dec 2nd, 2012, 09:35 AM   #3
KleineBiere
Senior Member

Join Date: Jan 2008
Location: Berlin
Posts: 1,603
Re: Elo-Ratings

Quote:
 Originally Posted by amirbachar The one that gives the best predictability to the rankings?
is there a formula?

might be a number between 22 and 25

Code:
result per k-factor

prediction	13,45	25	37,66

100%		100%	99%	99%
98%		98%	98%	96%
96%		96%	92%	93%
94%		93%	93%	92%
92%		91%	91%	88%
90%		90%	87%	86%
88%		89%	86%	84%
86%		86%	84%	81%
84%		85%	80%	80%
82%		82%	81%	79%
80%		82%	79%	76%
78%		79%	76%	77%
76%		78%	75%	74%
74%		75%	73%	72%
72%		74%	72%	69%
70%		73%	72%	69%
68%		71%	67%	68%
66%		70%	66%	65%
64%		67%	64%	62%
62%		65%	63%	61%
60%		63%	60%	60%
58%		62%	60%	57%
56%		60%	56%	57%
54%		56%	54%	53%
52%		54%	53%	52%

Dec 2nd, 2012, 09:44 PM   #4
amirbachar
Senior Member

Join Date: Apr 2006
Posts: 241
Re: Elo-Ratings

Quote:
 Originally Posted by KleineBiere is there a formula?
No, but in practice the MSE (http://en.wikipedia.org/wiki/Mean_squared_error) as a function of the K-factor decreases up to one point and increasing from that point, which allow us to make aמ adjusted binary search. I can give you some java code that searches the best value if you want...

 Jan 16th, 2013, 05:13 PM #5 Chilenaitor Senior Member     Join Date: Aug 2011 Posts: 6,587 Re: Elo-Ratings wait the next update
 Jan 31st, 2013, 02:43 PM #6 Chiquitita. Senior Member     Join Date: Apr 2010 Location: Bonn, NRW Posts: 20,704 Re: Elo-Ratings Very nice. Stephens already #22. __________________ come spring, come laughter come tears at night let me stay, let me stay a little while I ain't I'm not ready to go yet twitter
 Apr 9th, 2013, 02:39 PM #7 HowardH Senior Member   Join Date: Mar 2007 Posts: 10,979 Re: WTA Elo Ratings (08/04/2013) Great idea for a thread. Can you tell me whether, using Elo, Azarenka, Wozniacki, Safina, Ivanovic or Jankovic ever reached no. 1? I'm guessing Azarenka definitely did, and Ana Ivanovic maybe, the others I would guess no. If it's too hard to work out don't worry about it though. Last edited by HowardH : Apr 9th, 2013 at 02:54 PM.
 Apr 9th, 2013, 06:48 PM #8 KleineBiere Senior Member     Join Date: Jan 2008 Location: Berlin Posts: 1,603 Re: WTA Elo Ratings (08/04/2013) only vika did.(march 2012) safina was close...but lost the final of rg 2009 wozniacki has the best highscore (apart from azarenka)..but was behind clijsters
 Aug 3rd, 2013, 12:58 AM #9 Singleniacki ~*Princess Karolina*~   Join Date: Jan 2009 Location: Sydney Posts: 17,212 Re: WTA Elo Ratings (29/07/2013) What is an Elo rating? __________________ Wozniacki. Azarenka. Kleybanova. Dulgheru Halep. Muguruza. Kvitova. Hsieh. Gavrilova
Aug 3rd, 2013, 11:38 AM   #10
KleineBiere
Senior Member

Join Date: Jan 2008
Location: Berlin
Posts: 1,603
Re: WTA Elo Ratings (29/07/2013)

Quote:
 Originally Posted by Six Feet Under What is an Elo rating?
chess rating system. applicable in all h2h sports.

http://en.wikipedia.org/wiki/Elo_rating_system

 Nov 15th, 2013, 06:21 AM #11 chingching Senior Member     Join Date: Jul 2011 Posts: 18,116 Re: WTA Elo Ratings - revised (04/11/2013) No mention of Sasnovich __________________ Anett+Kaia+Carol+Lera+Eva+Sofishka+Mattias+ Kenneth+Jürgen+Alexander Kaia hit 24 Aces (the WTA record) vs Safarova Tokyo Round 1 2008
 Nov 20th, 2013, 06:39 AM #12 uchickenvn Senior Member     Join Date: Oct 2013 Posts: 148 Re: WTA Elo Ratings - revised (04/11/2013) What's Elo initial points for a player? 0?
 Dec 11th, 2013, 12:59 AM #13 GOATdin0931 Senior Member     Join Date: May 2011 Posts: 13,794 Re: WTA Elo Ratings - revised (04/11/2013) I dont understand how this works
 May 25th, 2014, 01:13 AM #14 bobito Tennis 'toonist     Join Date: May 2008 Posts: 6,144 Re: WTA Elo Ratings - revised (04/11/2013) I can see at least three of problems in using an Elo rating system for tennis. The first is the variable of the physical condition of the players. If a low rated player beats an injured or fatigued high rated player, their rating is greatly inflated. An extreme example of this would be Minella def S Williams 0-6 0-4 ret. Such a result would give Minella large but thoroughly undeserved boost to her rating. The same effect could happen to a lesser degree if a player is fatigued, either by having played a tough match late on the previous day or by having to play two matches on the same day. Secondly, it ignores the factor of the importance of the match. For example, should Petra Kvitova's win over Sharapova in the Wimbledon final be rated the same as Razzano's win over the same opponent in the 1st round of the Fed Cup (an event Sharapova cares nothing about) earlier that year? Tennis is a tournament sport and the ability to win the big matches should be a significant factor in rating them. Thirdly, the system doesn't change quickly enough for a sport where players can improve or decline quickly with age or form. Venus Williams, Stosur, Kanepi and Vinci's positions in your ratings are evidence of this. The system works well for board games and video games but I'm unconvinced that it applies quite so well to sport. __________________ @bobito64