ETwA

Tiddlywinks handicaps are a way of adjusting scores so that weak players participating in a tournament with strong players have a reasonable chance of winning.

__Examples__

One pair (handicap 6 and handicap 4) beats a second (handicap 5 and handicap 0) by a scoreline of 6-1. The handicap transfer is (5-2.5)/2 from the stronger pairing to the weaker pairing. Thus the adjusted score is 4.75 - 2.25.

A novice (handicap 0) loses to the world champion (handicap 7) in a game of singles by the scoreline of 0-7. The adjusted score after handicap transfer is 3.5 - 3.5.

Handicaps are normally fixed over the duration of the tournament. However, in some cases (e.g. the ETwA Singles Plate), players' handicaps are adjusted by +-0.5 after every game in which the adjusted score was 5-2 or higher.

Calculate the average rating of players in the tournament (assign novices a value of 1400 for this purpose). Then assign handicaps as follows:

rating minus average rating is greater than +325: handicap 7 rating minus average rating is in range +210 to +325: handicap 6 rating minus average rating is in range +100 to +210: handicap 5 rating minus average rating is in range 0 to +100: handicap 4 rating minus average rating is in range -100 to 0: handicap 3 rating minus average rating is in range -210 to -100: handicap 2 rating minus average rating is in range -325 to -210: handicap 1 rating minus average rating is greater than -325: handicap 0These values are roughly every 100 points (which is an easy to remember, but mathematically incorrect, method).

A useful guideline for setting handicaps (even if the above scheme is not followed) is that it is usually best that the average of the handicaps of players involved in the tournament should be about 3.5.

Alternatively, one could abandon the 0-7 handicapping scale, and use
actual player ratings and the predicted score function to predict what
point transfer should be awarded.
The ratings program recommends that the points transfer awarded in
each particular game be calculated according to:

POINTS TRANSFER = 3.55 * erf ((RATING + PARTNERRATING - OPP1RATING - OPP2RATING)/1600)This is the best handicapping system that the ratings program can produce. However:

- It assumes that ratings are accurate, which is not necessarily the case (particularly for those with low RRF values).
- It needs a calculator (or computer), or a table such as the one below.

Average Rating Difference | Recommended Point Transfer | Average Rating Difference | Recommended Point Transfer | Average Rating Difference | Recommended Point Transfer | Average Rating Difference | Recommended Point Transfer |
---|---|---|---|---|---|---|---|

0-10 | 0 | 194-215 | 1.0 | 428-454 | 2.0 | 779-833 | 3.0 |

11-30 | 0.1 | 216-236 | 1.1 | 455-482 | 2.1 | 834-897 | 3.1 |

31-50 | 0.2 | 237-258 | 1.2 | 483-511 | 2.2 | 898-975 | 3.2 |

51-70 | 0.3 | 259-281 | 1.3 | 512-542 | 2.3 | 976-1080 | 3.3 |

71-90 | 0.4 | 282-303 | 1.4 | 543-574 | 2.4 | 1081-1241 | 3.4 |

91-110 | 0.5 | 304-327 | 1.5 | 575-609 | 2.5 | >1241 | 3.5 |

111-131 | 0.6 | 328-351 | 1.6 | 610-646 | 2.6 | ||

132-152 | 0.7 | 352-375 | 1.7 | 647-686 | 2.7 | ||

153-171 | 0.8 | 376-401 | 1.8 | 687-719 | 2.8 | ||

172-193 | 0.9 | 402-427 | 1.9 | 720-778 | 2.9 |

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