Introduction

Firstly, many thanks to the West Australian Squash Association (www.wasquash.asn.au) for allowing Squashleagues.com to adopt their State ranking system. There are a variety of different systems out there but in the opinion of Squashleagues.com, theirs is the best we've seen (so far).

There are 3 'levels' at which the result of squash match could be evaluated:

1. Who won and who lost. Eg. Player A beat Player B.
2. Who won and who lost and how many games were won/lost. Eg. Player A beat player B by 3 games to 1.
3. Who won and who lost, how many games were won/lost, and what was the score for each of those games. Eg. Player A beat player B (9-3) (6-9) (9-6) (9-0).

The Squashleagues.com system goes to the second level. In other words, we believe that the number of games won and lost are significant for evaluation, but that the scores within each game are not.

Overview

When new players join Squashleagues.com, they are obliged to choose (from a drop-down list) a description of squash ability appropriate to themselves. Behind the scenes, each description of ability is associated with a value for 'ranking points', ranging from about 25 to about 300 points. Higher ranking points indicate higher squash ability, and vice versa. So new players are automatically assigned starting values for their ranking points.

With each successive match result that is entered involving s new player, the system automatically adds to or subtracts from the player's ranking points based on the outcome of the match.

A player is not awarded more points by playing more matches. Every match played could result in points being added to or subtracted from a player's ranking points.

Only matches played over the best of 5 (first to win 3) games are valid for inclusion. Walkovers have no effect on the ranking points of either player.

Points are added or subtracted based on the probability of the outcome of a match between two players. The more the ranking points differ between two players going into a match, the more likely it is that one will beat the other with a winning margin of 3 games to 0 (3:0). If two players' ranking points differ by 40 points or more prior to their match, it is considered extremely probable that the player with the most ranking points will beat the player with less points with a result of 3:0. Less than 40 points difference, and the outcome becomes increasingly less predictable.

Ranking points determine ranking positions. The person with the highest number of ranking points is ranked #1. The #2 ranked player might be 0.01 ranking points behind, or they might be 10.00 ranking points behind. This means that if the #1 ranked player loses to the #2 ranked player, their ranking positions will not necessarily swap: it will depend on how their ranking points are affected.

The maximum number of ranking points any player can gain (ie. after a 3:0 victory) is 6. The maximum number of ranking points any player can lose (ie. after 3:0 defeat) is 4.80. For any given match result, the winner stands to gain more points than are deducted from the loser. This means that over time there will be a very gradual upward trend in player ranking points.

Examples

Example 1: "A thrashing looks likely!" Before Player A: 200 ranking points Player B: 150 ranking points Points Difference: 50 Probable Outcome: 3:0 Victory to Player A After Result Player A Player B Player A:Player B Points +/- New Ranking Points Points +/- New Ranking Points 3:0 +0.00 200.00 -0.00 150.00 3:1 +0.00 200.00 -0.00 150.00 3:2 +0.00 200.00 -0.00 150.00 2:3 -2.88 197.12 +3.60 153.60 1:3 -3.84 196.16 +4.80 154.80 0:3 -4.80 195.20 +6.00 156.00

From Example 1 we can see that only a victory by Player B (the distinct 'underdog') over Player A will affect the ranking points of either player. Player A is considered so much better than Player B that it's impossible for Player A to gain any ranking points from this match. Likewise, no points can be taken from Player B for losing to Player A.

Example 2: "The clever money is on Player A" Before Player A: 170 ranking points Player B: 150 ranking points Points Difference: 20 Probable Outcome: Victory to Player A After Result Player A Player B Player A:Player B Points +/- New Ranking Points Points +/- New Ranking Points 3:0 +0.88 170.88 -0.70 149.30 3:1 +0.70 170.70 -0.56 149.44 3:2 +0.53 170.53 -0.42 149.58 2:3 -2.46 167.54 +3.07 153.07 1:3 -3.28 166.72 +4.10 154.10 0:3 -4.10 165.90 +5.12 155.12

From Example 2 we can see that since Player A is expected to beat Player B, only a small amount of points are awarded to Player A if the expected victory occurs. Relatively 'big points' are are only gained or lost in the event that Player B unexpectedly beats Player A.

Example 3: "Could go either way" Before Player A: 150 ranking points Player B: 150 ranking points Points Difference: 0 Probable Outcome: Uncertain After Result Player A Player B Player A:Player B Points +/- New Ranking Points Points +/- New Ranking Points 3:0 +3.00 153.00 -2.40 147.60 3:1 +2.40 152.40 -1.92 148.08 3:2 +1.80 151.80 -1.44 148.56 2:3 -1.44 148.56 +1.80 151.80 1:3 -1.92 148.08 +2.40 152.40 0:3 -2.40 146.60 +3.00 153.00

Example 3 shows how, when two players with equal ranking points play a match, the winner gains more points than the loser has deducted. Hence the slight upward trend in ranking points over time.

No system is perfect. The object of our system is to most fairly rank Squashleagues.com players based on their abilities as recorded by their match results. We welcome your comments and suggestions. Please send them to ranking@squashleagues.com. Thanks for your support.