How Boxed Ladder Results
are Processed

The new ladder is derived from the previous one in the following steps:

Pre-April, 2005

1. Unreported scores are recorded as zero, except in case of reported default.
2. Players with zero or one matches were not moved up or down, but were dropped by default. Their played matches are not counted.
3. The two highest ranked players in a box are lifted to a point just above the middle player in the next higher box.
4. The two lowest ranked players in a box are dropped to a point just below the middle player in the next lower box.
5. In case of two players tying, the stronger player is taken as the one who beat the other in their one-on-one match.
6. A player who dominates their box has the option of moving an extra box or two higher.
7. Players who played one or no matches are moved to the Ghost Ladder.
8. New players are seeded in.

April-June, 2005

The computation used to work up the March and April ladders was the following.

Unplayed matches are ignored.  There are no defaults.  If you beat a player rated better than yourself, it affects both your ratings more than if you beat a worse-rated player. If Lee Beachill beats you, it doesn't change the world much. But if you were to beat Lee Beachill, champagne's on the CRFC.

Let HIGHER be the higher-rated player.
Let LOWER be the lower-rated player.
Let DIFF be the difference in ratings, i.e. rating(HIGHER) - rating(LOWER).
Let PERC be the percentage of games won by the winner. (3-0 => 100%; 3-1 => 75% etc.)
Let STEP be the average difference in ratings between two adjacent players in the ladder.
Let ADJ_W be the amount added to the winner's rating.
Let ADJ_L be the amount subtracted from the loser's rating.

If HIGHER beats LOWER:
ADJ_W = PERC * STEP / (1.0 + DIFF/STEP)
ADJ_L = ADJ_W

If LOWER beats HIGHER:
ADJ_W = 2.0 * PERC * (STEP + DIFF)
ADJ_L  = 0.5 * PERC * (STEP + DIFF)

Gory

The gory details of what Harold does every month is here.

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