Historical Betfair BSPs

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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

Today I downloaded some data from http://www.betfairpromo.com/betfairsp/prices/index.php, as I fancied testing out a couple of ideas.

However, when analyzing my first spreadsheet, I soon discovered that backing everything to level stakes at Betfair's published BSP would have given me a double digit ROI! It wasn't like a 1,000 had come in and distorted the figures, either. I found the same on a couple of other spreadsheets I downloaded.

How accurate overall are Betfair's published BSPs?

Jeff
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LinusP
Posts: 1918
Joined: Mon Jul 02, 2012 10:45 pm

Did you take commission into account Jeff? I am fairly sure the data that betfair post is accurate.
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

dwbfpricesukwin13102014.xls
Yes

I've just randomly picked another spreadsheet (attached), and got 37% ROI!

Jeff
LinusP wrote:Did you take commission into account Jeff? I am fairly sure the data that betfair post is accurate.
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LinusP
Posts: 1918
Joined: Mon Jul 02, 2012 10:45 pm

Why do you have a +1 at the end of the equation?
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freddy
Posts: 1132
Joined: Sun Aug 01, 2010 8:22 pm

Whats the Average price of the winners Jeff ?

Edit : 11.47 in the spreadsheet provided, thats pretty high.

Think a larger sample is in order, when the short price favorites start winning it will probably even out.
Last edited by freddy on Sun Oct 19, 2014 5:03 pm, edited 2 times in total.
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

I take away 1 from the BSP, knock off Betfair's commission, and then add the one back on to get my return.

The column heading of P/L is perhaps misleading, as the positive figures represent the returns rather than the profits.

Jeff
LinusP wrote:Why do you have a +1 at the end of the equation?
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

Possibly.

Just did another one though (attached), and got 16% ROI!

Jeff
freddy wrote:Think a larger sample is in order.
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freddy
Posts: 1132
Joined: Sun Aug 01, 2010 8:22 pm

Anyone know what the average wining odds are for uk horse racing ?

that should help
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LinusP
Posts: 1918
Joined: Mon Jul 02, 2012 10:45 pm

You can't include your return as profit? Or am I missing something here (currently hungover so might be being stupid)
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PeterLe
Posts: 3729
Joined: Wed Apr 15, 2009 3:19 pm

Ferru123 wrote:Possibly.

Just did another one though (attached), and got 16% ROI!

Jeff
freddy wrote:Think a larger sample is in order.
Jeff
I think you've got that one wrong..
Using your spreadsheet, I make it -£63.94 ROI -12.39% :(

There is no +1 in the equation as Lian says..Example Take the second row..Ghost Dancer..winning at 1.62 would only give you 58.9p after the 5% commission..not as you have in your spreadsheet
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LinusP
Posts: 1918
Joined: Mon Jul 02, 2012 10:45 pm

From 2012..
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

Hi Peter

You're right! :oops: :lol:

Jeff
PeterLe wrote: Jeff
I think you've got that one wrong..
Using your spreadsheet, I make it -£63.94 ROI -12.39% :(

There is no +1 in the equation as Lian says..Example Take the second row..Ghost Dancer..winning at 1.62 would only give you 58.9p after the 5% commission..not as you have in your spreadsheet
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

Interesting.

Where did you download that spreadsheet from, out of interest?

Jeff
LinusP wrote:From 2012..
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NeilSpence
Posts: 78
Joined: Sun Nov 17, 2013 11:58 am

What happens if you just reverse all bets. Does the curve go the other way??
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Iron
Posts: 6793
Joined: Fri Dec 11, 2009 10:51 pm

Logically, if the BSP represents the true price over a very large sample of bets (which it demonstrably does), what will kill you long-term is the commission, so you'll be screwed whether you back or lay! :lol:

Jeff
NeilSpence wrote:What happens if you just reverse all bets. Does the curve go the other way??
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