The Last Homely House
Undying Lands => League Play => FotR League => Topic started by: TheJord on December 14, 2009, 11:20:11 AM
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For those interested in the maths behind your rating
For information, the ELO formula is as follows:
Say the rating of the better player is r1 and the rating of his opponent is r2. The probability that the higher ranked player wins (let us call this number P_F) can be computed by
P_F = 1 - 1/(10^(D*SQRT(n)/2000)+1)
where
n = the length of the match
D = absolute value of the current rating difference between both players = ABS(r1-r2)
The new rating of both players become then as follows:
a) If the higher ranked wins the match:
r1 + 4*SQRT(n)*(1-P_F) for the winner
r2 - 4*SQRT(n)*(1-P_F) for the loser
b) If the underdog wins the match:
r1 - 4*SQRT(n)*P_F for the loser
r2 + 4*SQRT(n)*P_F for the winner
All players start at rank 1500
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We actually use a much simpler version
» Using the old ratings oldA and oldB, the win probability for team A is calculated:
prob = 1.0 / (1 + 10 ^ ((oldB-oldA)/400.0))
» he change in the ratings is then calculated by:
score = 1 if A wins, 0.5 for draw, 0 if B wins
diff = 50*(score-prob)
» After that some rounding magic to integer is applied and the new ratings are calculated:
newA = oldA+diff, newB = oldB-diff
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Okay, I got lost somewhere in the middle... :/
Anyway, could you point me to the site you use? I'd like to run some "home made" leagues and it would be just great! :D
Cheers Jord!
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Ah maths - you've got ot love it :)
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Ahahah, or hate it... ;P
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Ah maths - you've got ot love it :)
Makes me think of this: http://www.youtube.com/watch?v=Pj2NOTanzWI
lol