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24.07.2011 21:39 - Betting exchange basics
Автор: martinstaniforth Категория: Спорт   
Прочетен: 914 Коментари: 2 Гласове:
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I think the phrase "betting system" is quite vulgar. It sparks a mental image of the degenerate gambler blindly backing the 2nd trap in the 2nd race at Portsmouth dogs, convinced there is a pattern emerging from the last 3 meets. Betting system is, however, the de facto phrase that describes our ultimate aim when trading a market on Betfairto extract as much money from our fellow punters as possible!

Tennis is the 3rd most popular sport to bet on at Betfair after football and horse racing. With a deep understanding of why it is so attractive to punters, you can actually become better at developing your own tennis betting system. So let’s start there.

Not all points are created equal

If you’ve come from a football betting background, you’re used to goals being pretty close to equally important to the outcome of a match. The timing of those goals will dictate the probability of a team going on to win, but the low scoring nature of football puts huge emphasis on each goal scored. It’s not the same with tennis. The unique scoring system and the absence of a timed finish leads to some points being hugely more important than others.

Take a look at that classic match between Ivan Navarro and Taylor Dent from the 2nd round of the 2009 US Open. From the outset our predictions model has Dent as a strong favourite, with an 83% chance of winning the match. The first point of the match sees Dent take a 0-15 lead against serve. His probability of winning the match now? Insignificantly higher! Nothing more than a rounding error in our first calculation. In the grand scheme of things, this point is unimportant.

Now let’s fast forward. Dent has come back from 2 sets to 1 down to take Navarro to a 5th set tie-breaker. Going into the breaker, with parity in the score, we now have Dent a marginal favourite with a 61% chance of winning the match (more on why later). In this video, we pick up the action at 3-2 Navarro, with Dent serving and exactly 50:50 for each player winning the match. We’ve overlaid the resulting probabilities for each player.

image

 

You see how huge the swings are!? Navarro peaks at 5-3 with a 78% chance of winning, 12 points later he’s packing his bags and heading back to Spain!

image Deeper and deeper down the hole

The model we use on our website is completely deterministic. Some stats go in; some numbers are crunched and out come a bunch of probabilities and some pretty graphs. This approximation will give you a pretty accurate view of the eventual outcome of the match. As no points have been played, we can’t draw conclusions about whether what we predicted is going to plan.

However, in the real world of in-play betting, events are stochastic and dependent on what events came before them! If you’re that way inclined, you can read a copy of Klaassen and Magnus’ seminal paper investigating the dependence of points in tennis. If you are not that way inclined, I can summarise the paper for you; the deeper in the shit you are, the harder it is to get out! Your Federer’s and Nadal’s are less affected, but they are affected nonetheless!

We’re 100% correct (in the end)

Looking back at our Navarro vs. Dent encounter, how did we get to that 83% chance of Dent being the victor? It’s all in the serve. Take each player’s percentage chance of winning a point on serve and his percentage chance of winning a point when receiving, compare this to the tournament average, the tour average, add some special sauce and we end up with Dent having a 69.75% chance of winning his points on serve, with Navarro a 63.5% chance of winning his points on serve. Feed this into the model and we get the magic number, an 83% chance of Dent winning over 5 sets at the US Open.

Take a look at the final stats. We can say with 100% certainty that the final point of the game results in an observed 69% chance of Dent winning a point on serve and a 67% chance of Navarro winning his points on serve. What about half way through the game? It"s a mix of what we predicted at the start and what we"re seeing on the scoreboard. It"s variable. We"re attempting to predict a moving target! This rollercoaster ride doesn"t even stop there. The mix we take when weighting our initial predictions with those we"re actually seeing during the game is dependent on the expected number of points remaining in the game, which is itself... a moving target!

Getting out of the hole

There are further dependencies in tennis. Over a best of three set match which goes to the third set, which player would you prefer to be on? The player who’s won the first set and lost the second, or the player who’s lost the first set and won the second?

Trawling the archives of 3 set hard court events from 2005-2010, we find 942 matches where the victor has a W-L-W set streak. There are 1043 matches where the winner comes through L-W-W. 53% of 2nd set winners go on to win the decider. On clay courts the advantage is even more pronounced. The W-L-W’s and L-W-W’s are 553 and 671 respectively giving us 55% of 2nd set winners going on to win the match. (3rd set grass court deciders are harder to come by, but the same effect prevails: 134 to 143 as above giving a 52% chance of an L-L-W over a W-L-W)

Momentum is the contributing factor. It’s subtle but significant. Throwing away a 1 set lead puts players in a massive trough, especially on clay!

Putting it all together

So... in order to predict the outcome of a match, we’re trying to predict the probability of each player winning his points on serve. Those probabilities are constantly fluctuating and the points vary in their importance. We know that if our player is in the shit he’s going to struggle to get out of it... but, if he does get out of it, he’s in a stronger position because of it!

Putting all these considerations together gives us.. volatility. Volatility leads to... uncertainty. Uncertainty results in.. opportunity! That’s why tennis betting on Betfair is so popular. The punter may not even known why they are attracted to it, but the natural ebb and flow of a tennis match can turn your fortunes in a second, and that’s why we all fell in love with gambling in the first place.

It’s not all in the numbers

The conventional wisdom of the British press was that Tim Henman wasn’t capable of winning a major because he didn’t have a convincing enough fist pump following the big points. His fist pumps per set (f.p.p.s.) was a lowly 0.8 average. Rafael Nadal’s fpps is closer to 10, which explains why he has won 9 majors by the age of 24. Andy Murray has a great chance of winning a major during his career as his fpps is 5. Like a lot of conventional wisdom in the field of punditry, this is complete bollocks! A player’s body language and its effect on outcome of a match are much subtler than that.

That’s right; those who are dubious that we can use the stats to predict the outcome of tennis matches will be pleased to hear this will only get us so far. Becoming a better tennis bettor requires an ability to read the human element of the game. This can’t be understated, so as an example we’ll put Andy Murray back under the microscope.

Murray does suffer from a mental fragility that is arguably worse than not being able to psyche yourself up for the big points; His occasional loss of concentration when in a winning position. When you know what to look out for, it’s as if he has a big pink square above his head that shouts "LAY ME!! Lay me like a Polish builder lays bricks!!" It’s about developing knowledge of each player’s quirks and using them to your advantage. Can you see when Gael Monfil is tensing his shoulders, leading to his next serve smashing into the net? How many bounces does Sam Querrey take before serving, and what does an extra two mean during the big points? Stay on top of this and you’ll see an improved betting P&L.

Getting good

This article may have disheartened you. "It’s all very well telling us about your model while you sit in your ivory tower, but how can I improve my in-play tennis betting??" First of all, remember your (likely) role in this. You don’t have to make the market at each and every point. It’s a simple game of higher and lower! Odds too high? You back. Too low? You lay.Being aware of the probabilities and importance of each point is useful but not essential. You can still find value based on your instincts alone. Here’s a couple of pointers to developing those instincts...

Keep it simple

There was a time when the market would underreact in a tiebreaker and overreact when a favourite player went a set up. This is now less pronounced, but there are plenty of similar simple trends which will lead to long term profitability if you can pick them out. Oncourt shows historical points data and is a good place to start when creating your own tennis betting system.

We explained how our probability of winning a point on serve is constantly fluctuating. Don’t underestimate the importance of this. It gives us a chance to hold up our hands and say "we got it wrong!" It’s something that the average punter takes a lot longer to come to terms with. We could provide you with further analysis on this, but would do so only when the words say more than a linkMatthew Walton’s observations are repeated match after match on Betfair. Heed what’s taking place in front of your eyes and adjust your betting accordingly.

When you’re new to Betfair, it’s very tempting to lay your player when he goes a set up. The sight of an all green potential P&L is satisfying, particularly to the newbies. The newbies, however, will almost never hedge to an all red position. Hedging is important, but has many nuances that may not be obvious at first glance. We’ll revisit this in later posts but for now, this will improve your in-play betting: Don’t hedge your winnings if you’re not prepared to hedge your losses. That bet you saw value in at the start of the match is likely to still be a value bet now your player is a set up.

Practice makes perfect

It can take a long time to build your own successful in-play tennis betting system on Betfair. Armed with the tools we’ve just given you, you’re well placed to start your own profitable system. Allow your betting (and stakes) to develop over time, learn from your mistakes and don’t chase loses.

That wraps up our "basics" series. Stay tuned for more top tennis betting analysis in the near future.

To view our Spread Betting or Fixed Odds articles, please visit our website www.tennisbetting365.com


Тагове:   tennis,   federer,


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Автор: martinstaniforth
Категория: Спорт
Прочетен: 7302
Постинги: 1
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