Players whose scores are to be compared must have an equal opportunity to win the same number of matchpoints. Factoring levels the playing field.
Two questions need to be asked about scores being compared:
1. Has everyone played the same number of boards? If not, multiply Boards/Boards.
2. Were the boards worth the same? Was a slam in one session/section worth the same as in other sessions/sections? If not, multiply Top/Top.
Sometimes you will need to do both.
Beware the awkward movements, the 1½ Appendix Mitchell where two EW don't sit out, a completed NS Rover where a NS pair doesn't sit out, the dread curtailed movements with skips, half tables or shared boards.
Example 1: 8½ tables play 9 rounds of 4 boards in a completed Mitchell movement.
As there will be a NS winner and an EW winner the two fields are not being compared with each other. The fact that one field plays fewer boards than the other does not matter. Also, every board is played 8 times so all have the same top of 14.
No factoring is required.
Example 2: Now consider the above movement being curtailed by one round.
All the NS field play the same number of boards so no problem. However, one EW pair has not sat out so has played more boards than all the other EW pairs. All the pairs that played fewer boards require their scores to be factored up. Boards/Boards. Multiply by 32/28
There is another problem. Set 8 hasn't taken a turn at the sit out table. It has been played 8 times (Top 14) and all the other sets have been played 7 times (Top 12). The boards are not worth the same. Top/Top. Multiply scores on all boards played fewer times by 14/12.
Example 3: A 2 week Competition.
Week 1 10 tables Share & Relay Mitchell, 3 boards a round, curtailed one round because of a power failure.
1 set has not reached the relay table so has been played at all tables so Top 18
1 set has not been shared so played 8 times so Top 14 so multiply 18/14
8 sets have been played 9 times so Top 16 so multiply 16/14.
Week 2 8½ NS Rover Share & Relay Mitchell, 4 boards a round. (Colds & Flu epidemic)
All boards are played 8 times so all have a Top 14 in Week 2. A Top was 18 in Week 1 so multiply Week 2 scores by 18/14.
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