Compiling Odds from a Rating System

[gavino]

Hi guys, Just joined the forum and loads of great advice and information but not exactly what I am looking for so I wonder if anyone can help. I want to be able to fairly quickly and mechanically create a set of horse racing odds based on a rating system that I am using. Basically, suppose I have a system that has rated four horses out of 100, and let us suppose that it accurately reflects their abilities in the conditions of the race (course, distance, going etc.). Ratings come out as follows: A 85 B 75 C 50 D 40 How could I theoretically turn this into a set of odds? What I think you can't do is what I have seen on some threads, which is as follows: The sum of ratings A to D is 250, so the odds are decided by calculating each horses rating over 250. e.g. C: 50/250 = 20% so the odds are 4-1 from the usual tables. The problem with this method is that it is likely that the 85 horse will beat the 50 horse every day of the week, so its real odds might be 20-1 or 30-1 or who knows?? The core of the problem is that all rating systems seem to rate each horse in a race individually rather than in comparison to the other runners. And odds are all about comparisons. Mark Coton has a method of sorts in the book 'Value Betting' but it doesn't seem very scientific and is not justified in any way (unless someone knows better?) although the odds it creates don't seem too bad. I am not saying that any system will be the be all and end all, it would just be great to have a reasonably reliable starting point! Can anyone help? Thanks Gavino

[Trilobite]

Re: Compiling Odds from a Rating System I use that method in my ratings program, and i can get it pretty close to betfair prices most of the time ( Not so much the big outsiders ! ). It does however get a lot of them with little or no form very wrong, but then we shouldn't ever follow ratings on face value. Here is an example from this week ( iam not sure how the formatting will come out !) First column is the Rating, Selection, BF price, My Price. 4:10 Pontefract Claiming Stakes (Class 4) 1m 102 Roar Of Applause 2.96 3.06 2nd 60 Star Links 5.10 5.23 59 All About You 3.15 5.32 3rd 37 Bea Menace 16.50 8.41 1st 22 Helieorbea 36.00 14.31 21 Pyrus Time 17.50 15.07 12 Charismatic Lady 44.00 25.37 4:40 Pontefract Handicap (Class 5) 1m4f 64 Oriental Cavalier 6.80 5.44 56 Persian Memories 6.20 6.18 47 Regal Lyric 6.40 7.44 3rd 43 Silent Act 3.65 7.99 2nd 38 Punch Drunk 18.50 9.03 32 Acquavella 27.00 10.93 29 Bow To No One 11.50 12.08 1st 22 Drum Dragon 11.50 15.97 16 Bubses Boy 30.00 21.26