I have been busy this week not just watching Cheltenham but also working on a Bayesian set of flat handicap ratings or should I say a Bayesian version of my flat handicap ratings.What has prompted me in this direction are two things. First of all my ratings do well but less well towards the off time of races which is a pity because the greatest liquidity on Betfair exists the closer you get to the off. My reasoning therefore is to try and produce the most efficient oddsline with the minimum amount of time and effort and with Bayes producing natural percentage chances of winning it is hoped that this may prove a way of cranking up the action towards the off.
The second reason is that I have already had some success in this area and hence the title of this post. No I do not have a wonderful oddsline approach to AW racing as the title suggests. What I have done in a completely unrelated area to my ratings is produced a novel oddsline approach. Now forgive me, for obvious reasons, if I do not spell out the nuts and bolts of this method, but I do feel there is a more general message which is worth passing on and could be of use to some of you.
My ‘novel oddsline’ approach initially did not generate profits, if memory serves me right I think it produced a small loss on Betfair. What I did next was simply to move the dividing line which specified bet or no bet. In other words where I had previously simply bet if the odds were greater than X I changed this to bet where the odds are greater than X + y%. I moved the line in the sand so to speak. This has now generated around +6% after commission profit off around 5,000 bets all under 10.0 on Betfair.
For older members of SmartSig this may well have a familiar ring to it. Some of you may recall an excellent article in the original SmartSig mag’ by an author called Filly. In this article Filly’s main point, if memory serves me well, was that just about any sensible approach to ranking or selecting horses could be made profitable by moving the threshold from a price point of view. At the time I was not sure whether I could buy into this. Some members were even wondering whether a forecast such as the Racing Post could be used and then, using an appropriate percentage above the forecast, a profit would ensue.
It seemed at the time to be pushing the boundaries of acceptance but the more experienced members of the group were more in the Filly camp of thinking than out. In fact I seemed to recall that it either won the article of the year award or came second.
I will keep you informed of progress on the Bayes approach but in the mean time remember not all fillies are bad bets.
If you recall the article or have some personal opinion on oddslines in general please leave a comment. All bloggers appreciate some sort of feedback.