Young Chelsea - Friday Scoring

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Friday IMPs

Cross IMPs Scoring

Since April 2006, Friday night club games have been scored by Cross-IMPs. Your score on any particular board is compared with those of every other pair sitting in the opposite direction to you, across the field. The total of these comparisons in IMPs is averaged to give you your score on the board.

The effect of this scoring is that you should be using team rather than pairs tactics throughout the competition, eg securing your contract rather than worrying about overtricks. This scoring method replaces the method which we previously used, known as "Butler" scoring, named after Geoffrey Butler, a former president of the now-defunct British Bridge League who devised the method as a means of scoring British international trials. Nowadays, Cross-IMPs are generally preferred to Butler scoring in serious competition.

 

 

Converting to Percentages for Ladder Purposes

Friday IMP scores are converted to percentages for inclusion in the Monday-Wednesday-Friday ladder database. The basis used in the YCBC computer system, founded on observations going back over 20 years, is that

• 60 % is equivalent to + 42.5 IMPs

• 70 % is equivalent to + 85 IMPs

These figures are based on playing 24 boards, the original Young Chelsea norm for Friday nights. However for some years we have now played an extra round on Fridays. So now when we publish an IMP result on Friday the figures need to be factored to take account of the extra boards played.

Here are the calculations to convert your score to the equivalent 24-board percentage for Ladder purposes:


Based on and Factored-Up to 26 Boards Played –

• 60 % is equivalent to + 46.0417 IMPs

• 70 % is equivalent to + 92.0833 IMPs

• 1 IMP corresponds to 0.2171946%

• You can use this table to convert your IMPs to their % equivalent when 26 boards were played

Based on and Factored-Up to 27 Boards Played –

• 60 % is equivalent to + 47.8125 IMPs

• 70 % is equivalent to + 95.625 IMPs

• 1 IMP corresponds to 0.20915%

• You can use this table to convert your IMPs to their % equivalent when 27 boards were played

Based on and Factored-Up to 28 Boards Played –

• 60 % is equivalent to + 49.5833 IMPs

• 70 % is equivalent to + 99.1667 IMPs

• 1 IMP corresponds to 0.20168%

• You can use this table to convert your IMPs to their % equivalent when 28 boards were played
  
  

The Scorebridge effect

We have recently changed our scoring programme, and now use Scorebridge, which produces extremely attractive results output for the web. However, in its latest upgraded form, it factors up the scores to match the greater number of boards played by either section, so you need to take that into account too if you wish to convert your score to its percentage-equivalent.

Eg: if you play 26 boards and your result on the web shows a score of 56 IMPs on a night when the other section played 28 boards, you need to convert your score, as displayed on the web, according to the formula for 28 boards rather than that for 26 boards. So, you calculate
50% + (56 x 0.20168%) which gives a result of 61.29%.

However, if there is only one section, or both sections play the same number of boards, you simply consult the table that applies for the number of boards you played.