2 research outputs found
A stochastic analysis of scoring systems
Many scoring systems can be seen as statistical tests of hypotheses. In tennis
singles, for example, the scoring system used can be seen as a test involving 2
binomial probabilities pa and pb, where pa (pb) is the probability player A (player
B) wins a point initiated by player A (player B). Tennis singles is thus a “bipoints”
game. The tennis scoring system is an inefficient test relative to the sequential
probability ratio test (SPRT) based on pairs of these points. When pa + Pb > 1
(the tennis context), an SPRT based on the “play-the-loser” (PL) rule is superefficient.
Chapter 2 shows that, when pa + pb > 1, there is in fact a spectrum
of super-efficient tests (with even durations) based on “partia1-PLV (PPL) rules.
The most efficient tests within this spectrum, when pa + pb > 1, are the SPRT
based on the (full) PL rule. Chapter 3 extends this spectrum of tests to produce
the total spectrum of tests (including those with odd durations).
Points within the tennis scoring system have different “importances” whereas
points within any member of the above (efficient) spectrum of PPL systems are
equally “important” when pa = pb. Intuitively, the differing importances of the
points within the tennis scoring system contribute to the inefficiency of that system.
Chapter 4 establishes a relationship between the efficiency of a bipoints
scoring system and the importances of the points within it; a relationship which
is used in Chapter 5 to show that the SPRT based on the PL rule has an optimal
efficiency property when pa + Pb > 1.
Chapters 6 and 7 address the question as to whether the super-efficiency of the
PL rule carries over to the case of tennis doubles in which there axe essentially 4
binomial probabilities pai, pa2 , Pbi and pb2 . Some asymptotic results axe achieved
although, generally speaking, they are of little practical relevance.
The particular scoring system used in tennis is analysed in detail in Chapter 8
and the methodology used is seen to be useful for analysing any “nested” scoring
system (e.g. tennis is 3-nested: points - games - sets). It was the study of this
specific scoring system and its inherent inefficiency which lead to the theory of
Chapters 2 to 7. A new tennis scoring system is proposed in Chapter 8.
Chapter 9 contains a brief discussion of some of the characteristics the designer
of a scoring system needs to consider and some results are given. The study of the
importances of points is extended in Chapter 10 and in Chapter 11 team play with
associated countback rules is investigated. The general conclusion is that “upwardnested”
countback systems (e.g. points - games - sets, in tennis) axe preferable to “downward-nested” systems (sets - games - points).
In Chapter 12 it is shown that the classical scoring system used in multiple
choice examinations can be considerably improved by modifying tha t scoring system
and instructing the examinees to cross any boxes known to be incorrect when
the correct box for that question is unknown
A statistical investigation of squash and tennis
This case study gives a probability model for the game of
international squash which is used to determine the probability that
a particular player will win a game, the expected duration of a game
and the expected number of handouts. The distribution of final point
scores is also calculated and a method is used to determine the order
of importance of rallies. Statistical methods are used to analyse
whether squash and tennis players have the capacity to be able to
"try harder" in certain circumstances. The results of these analyses
are used to revise the values for the probability that a particular
player will win a game given different state probabilities and are also
used to "explain", in mathematical and statistical terms, the
phenomenal achievements of Heather McKay and Geoff Hunt