Tennis puzzles

They’re not especially statistical, and not especially difficult, but I thought you might like to try some tennis-based puzzle questions. I’ve mentioned before that Alex Bellos has a fortnightly column in the Guardian where he presents mathematical puzzles of one sort or another. Well, to coincide with the opening of Wimbledon, today’s puzzles have a tennis-based theme. You can find them here.

I think they’re fairly straightforward, but in any case, Alex will be posting the solutions later today if you want to check your own answers.

I say they’re not especially statistical, but there is quite a lot of slightly intricate probability associated with tennis, since live tennis betting is a lucrative market these days. Deciding whether a bet is good value or not means taking the current score and an estimate of the players’ relative abilities, and converting that into a match win probability for either player, which can then be compared against the bookmakers’ odds. But how is that done? The calculations are reasonably elementary, but complicated by both the scoring system and the fact that players tend to be more likely to win a point on serve than return.

If you’re interested, the relevant calculations for all score situations are available in this academic paper, though this assumes players are equally strong on serve and return. It also assumes the outcome of each point is statistically independent from all other points – that’s to say, knowing the outcome of one point doesn’t affect the probability of who wins another point. So, to add to Alex’s 3 questions above, I might add:

Why might tennis points not be statistically independent in practice, and what is the likely effect on match probability calculations of assuming they are when they’re not?

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