Example Odds Line Calculation
Odd Lines: The Key to Finding Value in any Race
Profitable betting on horse racing revolves around finding value or, in other words, backing only those horses whose odds are longer than they should be, in your opinion. However, in order to do so, you must be able to identify such horses in the first place and that’s what creating an odds line is all about.
In simple terms, creating an odds line involves assigning an opinion, in the form of odds, to each horse in a race, which you believe accurately reflect its true chance of winning. Once you’ve created an odds line, you can compare your assessment of the odds with that of a bookmaker and, if the bookmaker is offering longer odds about any particular horse, you’ve identified a value bet.
If you’re sufficiently experienced, you can assign odds to each horse in a race using just the form book and your skill and judgement. However, the correlation between odds and ratings, which both reflect a horse’s chance of winning, means that it’s easier to create an odds line if you have a single rating for each horse. Creating your own ratings is the subject of another article altogether, but ideally you need a set of ratings, such as Topspeed ratings in the Racing Post, which take into account all the conditions relevant to the race for which you’re creating an odds line.
For the sake of this example, I’ve chosen the Betvictor Cheltenham Festival Pioneers Handicap, due to be run at 1805 GMT on Thursday, 24th January, 2013, completely at random and I’ll use Topspeed Ratings to demonstrate how to create an odds line.
The easiest way of creating an odds line using ratings is to add all the ratings together and divide each individual rating by the total to give the probability of each horse winning. However, one of the problems with doing this with Topspeed ratings is that they can be very close together, within a few pounds of each other, and consequently produce odds that are very close together. To solve this problem, instead of using the raw Topspeed ratings, I’ll use the square of the RPR as the basis for calculations.
Once you’ve calculated the individual probabilities, you can convert them to odds by taking the inverse or, in other words, dividing 1 by each individual probability and subtracting 1 from the result. Algebraically, Odds = (1 / Probability) – 1.
In this case, the odds line created is as follows.
Sherman McCoy 5.4
Ginger Fizz 8.8
Honourable Knight 6.2
The Absent Mare 10.9
Rocky Rebel 4.5
Reaction 7.5
Llamadas 7.5
Bold Adventure 6.5
We have effectively ignored three horses, Buckie Boy, Native Colony and Dr. Finley, who don’t have Topspeed ratings on the Racing Post racecard, so we don’t have a “true” odds line but, for a race chosen entirely at random, this one serves well enough to demonstrate the principles of creating an odds line.
The first thing that becomes apparent when looking at the odds above is that the race is quite competitive; we shouldn’t be looking to back any of the runners at decimal odds shorter than 4.5 or fractional odds shorter than 9/2. The next thing to do is to compare the odds in the odds line with those being offered by a bookmaker. The odds on offer are 7/2 Honourable Knight, 4/1 Ginger Fizz, 6/1 Sherman McCoy, 7/1 The Absent Mare, 8/1 Reaction and 10/1 bar. Our odds line suggests that Honourable Knight, Ginger Fizz, Sherman McCoy, The Absent Mare and, possibly, Reaction represent poor value, while Rocky Rebel, Llamadas and Bold Adventure represent good value.
By way of illustrating just how powerful the creation of an odds line can be, in the race itself Llamadas, who started at 10/1, beat Bold Adventure, also 10/1, by a short head. The Computer Straight Forecast (CSF) paid £108.45 to a £1 stake.
Free Download - Odds Line Calculation
We hope you enjoyed our odds line guide to help you identify value in horse races. Have any questions or comments just leave a comment below or feel free to send us an email.
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Excellent, well-reasoned and well-presented article.
Please keep ‘em coming, Willy!