Handicaps

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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.

How traditional handicaps work

The standard handicapping system is to assign all players at the start of the tournament with a handicap between 0 and 7. A handicap of "0" corresponds to "novice" standard, and "7" corresponds roughly to "national champion" standard. The actual game scores achieved are then modified by an amount that depends on the handicaps of the players involved. The handicap transfer is taken to be half the difference between the average handicap of each pairing.

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.

Recommended standard handicaps

Recommended standard handicaps can be calculated by the following method. This method is sensible in theory. However, it assumes ratings are accurate when in fact there may be considerable uncertainty in a player's rating. Thus the suggestions below should only be used as guidelines.

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 0

These 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.

Improved handicapping systems

An improved handicapping system could be implemented by setting new handicaps at the start of each game, allowing for the standard of the players in that game, rather than setting a handicap for the whole tournament based on the players within it. This could be done on the same 0-7 handicapping scale as described above.

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.

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