From 1^st January 2004 GB rankings will be calculated according to the Glicko system, this will be updated monthly. Follow this link to view pre 2004 rankings.

Glicko a Brief explanation

Unlike earlier UK ranking mechanisms Glicko determines players comparative abilities by looking at game results between players rather than the overall position achieved in a competition. Also unlike earlier ranking mechanisms Glicko represents the lifetime achievement of a player rather than their recent form.

Under this system two values are calculated for each player.

Rating Level

This is a numeric value representing the estimated relative playing strength of each player. The higher the value, the stronger the player. If two players are equally rated, then based on the information to date and their reliabilty (see below), there is expected to be a 50% chance of either player defeating the other in a competitive game of DBM. The greater the difference in rating levels, the greater the expectation that the higher rated player will win a competitive game of DBM. Rating level is calculated on results from each valid game played in rated competitions. The previous rating level is adjusted depending upon whether the player has performed better or worse than expected based on their past results and the quality of the opponents they faced in each competition.

 Statistical Reliability

This is an indicator of how accurate an estimate of the rating is likely to be, or in other words, how much trust can be placed in it. As more games are played the ratings level becomes more reliable. The reliability is also affected by opponents reliability so the better their reliability the greater the improvement in own reliability. However the reliability measure is subject to decay with time. That is, the longer a player goes without competing, the less reliable his rating level becomes.

Note that low numbers represent greater reliability than higher numbers.

Rated Competitions

All competition types (i.e. singles, doubles, 15mm, 25mm) will be included within a single set of rankings, with no weighting applied to any competition.

All DBM competitions which include 4 or more rounds held in Great Britain are eligible for inclusion. Opponents must have the same AP and there must be no 'special rules'.

For a competition to be included event organisers must provide suitable data which as a minimum must include a full listing of who played who in each round and the results of the matches. See the BHGS web site results pages for  typical examples of this. This information must be presented as an excel spread sheet, and sent to Alan Cutner the BHGS Glicko co-ordinator who can provide help and advice to achieve this. If the event results are also to be listed on the BHGS web site a copy of the results must also be sent. Unfortunately we will not be able to include data that does not fulfil our minimum requirements.

There will be no 'opting out' of rankings where a player actually competed in a rated competition. 

Doubles

In doubles competitions the gain/loss of ratings points will be shared by the two players. The gain/loss will be apportioned between them according to their relative abilities as determined by a Glicko calculation. For example two playing partners that would be forecast to draw if they played against each other will share the gain/loss equally, whilst a team whose forecast result would be 7-3 between the partners will share the points on a 70/30 basis.

Information

We have used Data from a number of past events in order to arrive at a staring position (December 2003). The events chosen are those where we have reliable data and a schedule of these is displayed below.

The Glicko system will not be used to calculate the annul Society of Ancients National Championships. Instead this will be calculated on a similiar basis as before, using a Grand Prix system which will also be the basis for selecting teams to represent us in international competitions. Glicko Rankings will be used to determine competition seedings.

Updated tables will be published monthly. The published information will consist of 3 lists:

Full Ranking

This will list all players qualified for a GB ranking. To qualify a player must have played at least one rated game in the previous 12 months, and have a statistical reliability of 100 or less (this represents approx. 20 games over the past two years).

Competition organisers and umpires will be credited with the number of games played at that competition for reliability purposes. This in order that they are not penalised for playing insufficient games to retain a full ranking. The calculation of ranking points is unaffected.

Full Alphabetic List

This will list all players with a rating in alphabetic sequence, whether qualified for a full ranking or not. Where a player does not have a full ranking their 'notional ranking' will be shown. This is the position they would have if there was no qualifying criteria. A notional ranking is shown in the format '[ * nn * ]'.

Armies Used

This displays the armies used in all included events. It should be noted that for the purposes of this table all scores are converted to the   10-0 scoring system (NB 32-0 scores are divided by 3.2).Draws are games that result in a 5-5 score. All other matches are considered as a win or a loss.

UPDATED SCHEDULE OF EVENTS USED TO COMPILE INITIAL THE GLICKO RANKINGS