Accuracy of Betfair starting prices

I have a feeling that I am going to have a need to refer to accuracy of Betfair starting prices in my future articles. For that reason I decided to create nice chart and table that compares the expected strike rate and actual strike rate in different odd ranges.

In odd ranges I used the fractional odd increments as limits for a range. Data covered is all races ran in UK and Ireland in 2013. And I decided to limit analysis this time to odds under 10.0.

Let’s start with pretty pictures and present the data in line chart form where we can see that actual strike rate follows the expected strike rate pretty well, biggest differences are in the shorter odds, especially those under evens but after that it balances out and differences are not too big.

And then the same in table form.

FractionalDecimalExp.SRAct.SR
1/41.2585.26%81.73%
1/31.3377.38%70.59%
2/51.473.03%71.72%
1/21.569.03%64.14%
4/61.6763.05%61.61%
1/1254.27%55.92%
11/102.148.98%48.26%
6/42.543.29%42.04%
7/42.7538.1%38.61%
2/1334.77%35.3%
9/43.2532.08%31.42%
5/23.529.68%28.32%
11/43.7527.62%27.38%
3/1425.85%25.84%
10/34.3324.02%22.79%
7/24.522.67%23.52%
4/1521.12%21.96%
9/25.519.11%19.34%
5/1617.44%17.34%
11/26.516.05%16.16%
6/1714.85%14.85%
13/27.513.84%13.66%
7/1812.94%11.21%
15/28.512.16%12.11%
8/1911.45%12.24%
17/29.510.84%10.48%
9/11010.27%10.28%

My betting workflow

I use two approaches to my betting – for a while now I have been building an Bayesian betting system which calculates odds for each race on any given day. It is still work in progress but results so far are promising. And other avenue is betting systems where selections are made mechanically based on set of criterias.

In both cases I use same database to give me handy list of selections each day. So once the system is built and tested it is trivial to get the selections each day. That way it is easy to concentrate on the interesting parts and not spend lot of time in the menial stuff.

As a source of data I use excellent Racing Dossier by Michael Wilding of Race Advisor fame. Within the software there is handy export option to spit out csv-file of days races and set ratings that one has defined.

Once I have the data I upload it to my system and it will calculate the odds and prepare the list of selections. After that it is just matter of placing the bets, for them I use bunch of BOG bookies as well as Betfair. For figuring out which bookmaker to use I check Oddschecker for summary of odds available.

If you like to read more about my Bayesian system, I have written three part diary describing it for SmartSigger magazine. First part was published in July 2014 issue, second in August and third one will be in the yet to be released October issue.

Read Peter Mays books!

I recently finished Peter Mays book In Search of the Winning System where he accounts his personal journey to devise systems that win money from betting on horses. And I dare say that it is one of the best books I have read on the subject so far. Especially if combined with his other book Forecasting Methods For Horseracing.

Of these two, Forecasting Methods is the more theoretical book which covers the ways of devising betting systems from more mechanical angle and Search looks at systems more from point of view of possible angles that could be used as basis for a system. Of course there is a lot of anecdotal content in Search and I think back cover blurb from Amazon describes it well enough.

Charts Dr Peter May’s obsession with betting on horseracing. In this book the author of the acclaimed Forecasting Methods For Horseracing presents the story of his search for profitable methods, the mistakes he has made, the valuable lessons he has learned and the knowledge he has gained from like-minded racing enthusiasts who have contributed to his 40-year betting apprenticeship. Add to that a range of amusing anecdotes, a detailed analysis of the key race types, and a list of the betting systems he currently employs and you have a book that will make you smile, make you think and probably make you money.

Without repeating myself too much, both books are well worth a read and I don’t think I can recommend them enough. Go read them. You can also download two of his earlier books for free from here. I haven’t read them yet myself, if you have, please let me know in comments.

Beginning of an era!

Welcome to this new blog. Where I am going to write about horse racing and betting. Name of the blog comes from two words Racing and Analyst, simple as that. At least initially blog is going to concentrate on flat and jump racing from UK and Ireland. My analysis style is systems and statistics so the content of this blog will lean on heavily in that direction.

But this short introduction will have to do for now, I need to get back to final tweaks and adjustments to get this train moving. Hope to see you back when I have actual content to show.

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