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## How do Real Tennis handicaps work?

Even the most experienced of players are at times confused by the apparent black art behind handicap adjustments.

Handicapping is only ever an approximation of relative skill level, whose purpose is to enable competitive play between players of different standards. Match results will naturally vary, such that if A has a better handicap than B, it doesn’t mean that player A will always beat player B – but over a number of matches, A would be expected to win more often than not. Playing off handicap evens things up and gives both players scope to prove they are better than their rating.

A handicap difference of 6 points is taken to mean that a game played from a 15–0 start will be equally likely to be won by either player. If those players instead started each game from 0-0, then the better player would be expected to win 2 out of 3 games. This is the statistical basis of the likelihoods of different outcomes based on actual handicaps and the effective handicap differences played.

The handicap difference between two players is reviewed in light of a match result between them, to decide whether that difference is likely to still be accurate, or needs adjustment. If a change is needed, then each player’s handicap is altered by the same amount, one favourably, the other not. Thus your handicap is based upon your whole history of recorded results, and the more results you record, the more accurate it is likely to be.

To determine the size of any handicap adjustment, the system considers the match result in the context of the expected outcome, which depends on any difference between the players’ actual handicap difference and the handicap difference at which the match was played.

The system works out the games won by each player, adding an extra game for each set won. So if A recorded a score of 6-4, 3-6, 3-5 against B, this would 12-15 in games, plus an extra point each for the completed sets, so 13-16. So A won 13/29 or 44.8%. (We'll refer to this as the 'result %' and the points as ‘outcome points’ to distinguish them from handicap points and the points in each game!)

The expected outcome depends on whether the handicap played reflected the actual handicap difference. If it does match, then the effective handicap difference is 0, and the expected result is 50% each. If it doesn’t match, then the expected result varies according to the difference between actual and played handicaps. If the real handicap difference is 2 points but the match is played off 0-0, then the weaker player is under-compensated by 2 points, and so is expected to win fewer than half of the games. The approximate proportion of games the weaker player is expected to win for each effective handicap difference value is shown in the table below (in this case 43.3%):

Level |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |

50% |
46.7% |
43.3% |
39.7% |
36.6% |
33.3% |
29.6% |
26.5% |
23.1% |
19.4% |
16% |

The statistical challenge lies in how much deviation from the expected result is acceptable before adjustment of the handicaps is required, and how much adjustment is then needed. Current practice recognises three outcomes:

- a draw i.e. the result matches the expected outcome plus or minus around 8% (so approximately 42-58% for Level)
- a small win/loss, i.e. outside the draw range, which moves the handicaps by +/- 0.2
- a big win/loss, which moves the handicaps by +/- 0.6, and is applied to extreme cases of the above which occur less often than 1 in 10 (result % outside approximately 30/70% for level).

(There is a move to replace the arbitrary distinction between small and big result adjustments with a sliding scale of adjustments ranging from 0.2 to 1.0 according to the scale of the result, but this has been awaiting international handicap committee approval for some time.)

This mechanism requires that the 'better' player wins well enough to justify the handicap difference. It can turn out that though the better player wins the match, it records as a handicap draw, or even a loss, because the winning margin was not sufficient to justify the handicap difference.

NB The approximate percentages given above are for guidance only and are not absolute. The system in fact uses a table of threshold values measured in games and sets won, according to the effective handicap difference played (as described above) and the total number of outcome points (as above), which progressively increases the significance of each result according to the number of games played within it. For each combination, a set of threshold values is defined which delimits the ranges of outcome points which constitute a big loss, loss, draw, win or big win.

The table is attached below, and as an example, if there are 14 points for, say, a correctly handicapped 8-5 win, the entry for 0 difference and 14 points shows that 0, 1, 2 or 3 games means a big loss, 4 or 5 a loss, 6, 7 or 8 a draw, 9 or 10 a win, and 11, 12, 13 or 14 a big win. So the 8-5 result, reflected as 9 points to 5, is a win/loss.

Click here for a table of the handicap thresholds

Other features which might affect your handicap include the following.

- Home court advantage, to reflect the relative unfamiliarity of a visiting player (so a visitor's handicap is deemed to be higher than shown).
- 'Volatile' players whose handicaps are provisional i.e. changing so quickly that special steps are needed to adjust them faster by using stable players as yardsticks (doesn’t necessarily mean they are temperamental!)
- Weightings, to increase the size of handicap adjustments after more important club competition and National League matches.
- Pro adjustment. Although handicaps are generally calculated by computer, Andrew and Craig can manually disarm bandits improving too fast for the system!