| How ACF Ratings Are Calculated
The ACF Rating is an indication of a player's skill relative to that of his / her opponents'. This rating is a function of whom a person plays and the match points they receive. It is not a function of which tournaments a player attends or of which division he / she enters.
ACF Ratings Formula
Rp = Rc + Window_Size * (W - L) / N
where Rp = performance rating,
Note: Ratings are computed by how many games were played in each round and then averaged with the last 128 games.
The Window_Size Constant
For example: Suppose a player wins three rounds and loses one round. That player has a Win Rate of W / N = (3 wins) / (4 total rounds), or 75 percent. Plugging W, L, and N into the ratings formula, we have Rp = Rc + 400 * (3-1) / 4 = Rc + 200.
Similarly, if your win rate is 50 percent, then your rating would be equal to the average rating (Rc) of your opponents. (See if you can compute this as above.)
Note: Most players have a win rate of around 50 percent but play in different tournaments and divisions.
For example: Suppose your rating is 2000, and your opponent's rating is 1650. Then we have (2000 - 1650) / 400 = 87.5 percent. For the purposes of calculation for that round, your opponent's rating will be computed as 1650 + (3 / 4) * 400 = 1950.
This anomaly occurs in less than ten percent of all rounds played. Most instances occur in small tournaments.
Note: An opponent's rating is always assumed to be 1000 or above.
The Game-Weighted Average
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