Set fair for Tennis value

In terms of matches we’re now over half way through the US Open, which leaves us in an excellent position to assess the special offer currently on offer from Paddy Powers. The leading Irish firm are offering money back on all single bets (up to a maximum stake of €100/£100) if your selected player loses his/her last set to a tie break. Clearly it’s of value, but the question we want to look at here on the BetPreviews betting school is – how much value, exactly?

As with all things, the best place to start is with the data. At the time of writing, 23 games had led to a refund, based on a sample of just over 200 matches. However this is actually much lower than would be expected at first glance. Statistically speaking, the tournament has been consistent with Tour statistics in that roughly one in six sets have been decided by tie break. If these were evenly spread out over the course of matches, then we’d expect that one in six matches would lead to a refund – however this doesn’t take into account the stamina issue, which is particularly applicable in the women’s game (over 60% of refunds have been in men’s games). An underdog might find it a lot easier to stay competitive in the first set, while a better player will begin to exert their dominance more and more over time.

Thus, we can see why one in six sets becomes one in eight matches – however in this regard, the bookies have probably been a bit fortunate, since usually the gap here is not as wide.

If we take it that the true odds of the last set being a tie breaker is roughly around 14% or one in seven – and certainly we should see more and more of this as the tournament progresses and as games become more even in theory – then logic dictates that each player starts each even game with a 7% chance of losing in a refund situation. This is skewed of course for long odds on shots, but those are best avoided anyway since there is a much greater chance of one-sided sets.

Of course as a bettor, what you need to know is how this affects the odds.

If we take a match where the betting with the bookie is 8/11 vs even money. In real terms, if those odds are correct, this equates to a 54% vs 46% game. That would suggest that the 14% chance of losing would be split 7.5% vs 6.5%.

The favourite now has a 54% chance of winning, a 7.5% chance of refund, and a 38.5% chance of losing. Using expected values, that gives the bet that returns €1 a value of roughly 59 cent – meaning that this is now a 7/10 shot in true terms, or that the bookie would normally offer 8/13 about it.

Or, to distil the whole thing down, this special offer is worth two ticks of price. If your selection is 4/6 with this offer, that’s the same value as backing him or her at 4/5 without the offer. So by extension, if the best price in the marketplace is 5/6, take the 5/6. If the best price is 8/11, take the 4/6.

 

About Kevin Egan 130 Articles
Kevin Egan is one of Ireland's leading GAA tipsters. He has previously served as GAA odds compiler for a number of major bookmakers.

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