Il giorno Wed 15 Mar 2017 09:57:34a, *Greg* ha inviato su
Post by GregC'è un modo semplice, una formula, per attribuire il punteggio Elo
alle squadre di calcio? Sarebbe fattibile? Come bisognerebbe
procedere?
http://www.eloratings.net/
The World Football Elo Rating System
The World Football Elo Ratings are based on the Elo rating system,
developed by Dr. Arpad Elo. This system is used by FIDE, the international
chess federation, to rate chess players. In 1997 Bob Runyan adapted the Elo
rating system to international football and posted the results on the
Internet. He was also the first maintainer of the World Football Elo
Ratings web site. The system was adapted to football by adding a weighting
for the kind of match, an adjustment for the home team advantage, and an
adjustment for goal difference in the match result.
These ratings take into account all international "A" matches for which
results could be found. Ratings tend to converge on a team's true strength
relative to its competitors after about 30 matches. Ratings for teams with
fewer than 30 matches should be considered provisional. International
football data is primarily from rsssf.com, theroonba.com, and soccer-
db.info. Other sources are listed on the football links page.
The ratings are based on the following formulas:
Rn = Ro + K × (W - We)
Rn is the new rating, Ro is the old (pre-match) rating.
K is the weight constant for the tournament played:
60 for World Cup finals;
50 for continental championship finals and major intercontinental
tournaments;
40 for World Cup and continental qualifiers and major tournaments;
30 for all other tournaments;
20 for friendly matches.
K is then adjusted for the goal difference in the game. It is increased by
half if a game is won by two goals, by 3/4 if a game is won by three goals,
and by 3/4 + (N-3)/8 if the game is won by four or more goals, where N is
the goal difference.
W is the result of the game (1 for a win, 0.5 for a draw, and 0 for a
loss).
We is the expected result (win expectancy), either from the chart or the
following formula:
We = 1 / (10(-dr/400) + 1)
dr equals the difference in ratings plus 100 points for a team playing at
home.
Sample Winning Expectancies
Difference
in Ratings Higher
Rated Lower
Rated
0 0.500 0.500
10 0.514 0.486
20 0.529 0.471
30 0.543 0.457
40 0.557 0.443
50 0.571 0.429
60 0.585 0.415
70 0.599 0.401
80 0.613 0.387
90 0.627 0.373
100 0.640 0.360
110 0.653 0.347
120 0.666 0.334
130 0.679 0.321
140 0.691 0.309
150 0.703 0.297
160 0.715 0.285
170 0.727 0.273
180 0.738 0.262
190 0.749 0.251
200 0.760 0.240
210 0.770 0.230
220 0.780 0.220
230 0.790 0.210
240 0.799 0.201
250 0.808 0.192
260 0.817 0.183
270 0.826 0.174
280 0.834 0.166
290 0.841 0.159
300 0.849 0.151
325 0.867 0.133
350 0.882 0.118
375 0.896 0.104
400 0.909 0.091
425 0.920 0.080
450 0.930 0.070
475 0.939 0.061
500 0.947 0.053
525 0.954 0.046
550 0.960 0.040
575 0.965 0.035
600 0.969 0.031
625 0.973 0.027
650 0.977 0.023
675 0.980 0.020
700 0.983 0.017
725 0.985 0.015
750 0.987 0.013
775 0.989 0.011
800 0.990 0.010
Address : <http://www.eloratings.net/system.html>
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