Betfair exchange prices

Compared to the sportsbook they are mad and Berger is 46 according to datagolf

The sportsbooks are mad, they’re charging 50% juice

Sportsbooks = huge overround
Exchange = market price with money from various sources and models, tiny overround
Datagolf = one model that is bound to have differences to the exchange


Just an unrelated question from me - why is Stricker top 20 on betting results 0.06 and then
0.11 on the finish position tool thanks :blush:

And duf is EV 0.02 on betting results and 0.11 on the finish position

There is a lot of value to be had in the exchanges using our model. That is where the best prices are. We had a subscriber (with the help of Bet Angel software) set up a pretty-well automated bot that traded off our model prices for the last 1.5 years with some solid returns. He recently stopped as it was not completely automated and was taking time to maintain.

I wouldn’t worry too much about your bet sizes, just make sure you aren’t putting your entire bankroll at risk. For Outrights we typically use a Kelly fraction of 0.1 or so. Maybe check out this earlier thread on bet sizing.


Two reasons there can be differences: 1) Betting results shows EV on that specific bet size, e.g. if the EV is 11%, then the EV on a 1-unit bet will be 0.11, but on a 0.5 unit bet it will be 0.055, and 2) The odds may change. For example, Stricker’s outright odds have shortened quite substantially since we placed our bet on him.

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Do you know of anything similar to Bet Angel that is available in the US?

Was he covering place markets or just outright?
I come from a background of believing the exchange is the true price, and since subscribing to datagolf have been placing exchange bets using more than just datagolf model aiming to beat closing line exchange price.

Although I am softening to the idea the exchange is not 100% accurate on golf and you can still beat closing line price, hence curious how this subscriber was fairing just using datagolf. (although if he stopped due to time it suggests the margins were low).

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Would you recommend laying players that your model hates ? Would that increase profitability thanks

Did that guys automated betting back only or lay and back

Outrights, place markets, and near the end was doing matchups as well. His margin was not that small, but you are taxed very heavily by Betfair once you reach a certain level of profitability. The closing line at the exchange is presumably pretty accurate, but in the days leading up to that there seem to be plenty of inefficiencies. Our model has done well betting T5/T20s at bookmakers (or at least we were doing well until books started opening a lot closer to our numbers), and you can almost always find a better price on the exchange.

When you say ‘beat closing exchange price’, do you mean to be profitable betting against the closing number? Or do you mean to place your bet at odds better than the closing price (I assume the latter, given you said you are treating the exchange price as ‘truth’).

Mainly backing. He had certain (rare) cases where he would lay a player he had previously backed.

In theory backing/laying should work equally well, although I would probably be more comfortable backing. If you are laying you will likely need a more sophisticated bet sizing strategy, as in golf you can have big liabilities if you are laying Longshots (which pretty much every golfer is in the outright markets).

FYI, TradeSports avoided this problem by having 30-40 listed golfers and a “field” selection. The markets were linked which means that you could short multiple golfers and the amount frozen in your account would be worst case loss. That means once you shorted a golfer, you freed up more cash in your account by shorting more golfers.

Win markets are great once you start shorting 10-20 golfers and trade positions like crazy. Since you make your prices you get to feel what it’s like to be a book. (Spoiler alert: it’s awesome)

As for Betfair i don’t know why they increase the tax the more profitable you are. I’m guessing this is because it’s not a true “exchange” and Betfair employees are using beards to create markets. In general you want to provide incentives to increase volume.

I meant I now aim to get the bet on at better odds than the closing price.

But I am starting to think it might be possible to be profitable betting against the closing number on the exchange too if its someone less fashionable and the smart money can get on what it wants without ever pushing the price down as low as ‘true’.

Betfair is the exchange, so much so that if it goes down in the UK other exchanges and even some books struggle to function.
They know the strength of their position so want a cut from the successful traders, hence their ‘premium charge’. This is still fairer than some of the other exchanges imo and because of the volumes available the big traders will stick with betfair more often than not

Amusing to me that datagolf’s +EV Open bets are basically all North American PGA Tour players with no success at previous Opens.

Literally, the top seventeen golfers on bet365 don’t have a single top ten at a prior Open Championship. Cink at 18th is the first one to do so.

I think next week’s going to be the hardest one of the year to bet on, to be honest. To use a tennis analogy, it’s a clay court specialist playing at Wimbledon. Of course some of them are going to adapt, but there are so many top class players who can’t.

You can’t really account for that in the numbers, but honestly it’d be a week where blindly following DG would probably get you in trouble.

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are you trying to say you don’t think Chuck Hoffman will play well next week? :laughing:

Weeks like this on the European Tour are one of the frustrating things about having a fairly rigid, automated model. It’s hard for us to adjust things on a weekly basis, even when it’s pretty clear something needs to be adjusted. Hopefully we will be able to make some tweaks before next week. Although I wouldn’t be surprised if our numbers on those experience-less Americans are at least directionally correct relative to the market (whether it’s enough to be truly +EV, is another question). Maybe just reduce the Kelly fraction…

Actually you don’t need to make adjustments, just give us a heads up on the weekly thread.

Of those seventeen players, Hoffman’s top 20 finish in 2017 and 2018 makes him one of the better prospects. I was mentioning it as a note of caution for people intent on going mad on the exchange prices.

Majors (apart from the Masters) are amongst the hardest weeks of the year because the markets are sculpted to within an inch of their life by the start of the week, and it’s getting increasingly hard for non-fancied players to win them. For a largely unknown winner, you’d need to go back to Keegan Bradley in 2011.

I’d much prefer a bog standard week featuring a rubbish European Tour event in Oman or Kenya and a PGA event where someone like Hoffman is the 18/1 favourite over a major.