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Informations about the package ers
ERS (EGF Rating System)
The rating algorithm was updated starting 2021. The whole database from back in 1996 was recalculated with this algorithm. You can find the old algorithm here.
- Ratings are updated by:
r' = r + con * (Sa - Se) + bonus
r
is the old EGD rating (GoR) of the playerr'
is the new EGD rating of the playerSa
is the actual game result (1.0 = win, 0.5 = jigo, 0.0 = loss)Se
is the expected game result as a winning probability (1.0 = 100%, 0.5 = 50%, 0.0 = 0%). See further below for its computation.con
is a factor that determines rating volatility (similar to K in regular Elo rating systems):con = ((3300 - r) / 200) ^ 1.6
bonus
(not found in regular Elo rating systems) is a term included to counter rating deflation:bonus = ln(1 + exp((2300 - rating) / 80)) / 5
Se
is computed by the Bradley-Terry formula:Se = 1 / (1 + exp(β(r2) - β(r1)))
r1
is the EGD rating of the playerr2
is the EGD rating of the opponentβ
is a mapping function for EGD ratings:β = -7 * ln(3300 - r)
Usage
Test
All versions of ers with dependencies
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Requires
php Version
>=7.0
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