Starting and forecast odds

Question

A follow up post to my one earlier this morning (which I promptly closed when I saw starting_price as a field in historic_runners_beta)...

My historic model runs through 1000s of days of historic race data and provides model parameters going forward when choosing a future pick.  A big issue for me is odds.  Prior to my post this morning, I was using forecast odds for both historic and future picks and the reality was that the historic PnL was inflated because most of the starting prices seem to be lower than the forecast odds.  Come race day, I was picking the same horses but the returns were lower (much lower in some cases).

I'm wondering if anyone has any ideas how I can circumvent this issue.  Short of running my model minutes before each race with amended market odds, I'm not sure how this can be improved.  Running the historic model with starting price seems to give accurate historic returns but I can't use them on 'today's races.

Thanks

Answer 1

The starting price is the starting price - so in fact it is unknowable until after any race has in fact started; it is the last price for each horse at which decent money was laid just before the off.

The market is dynamic before that point, and in a constant state of flux, so the best that can be achieved in terms of "knowing" the starting price in advance is an estimation.   That estimation will of course be more accurate the closer to the race time off that any prices are collected.   The Betfair API is probably your best option for grabbing back prices just before any race; however, that itself is a different system to the starting price mechanism - a comparison of these prices and more is covered in this blog piece which may be informative, and also discusses the value of forecast prices in the Smartform database and betfair early prices (which are included with the Betwise oddslines):

https://blog.betwise.net/2019/07/08/bookmaker-vs-betfair-odds-comparison/

Comments

Thanks for the response, Colin, much appreciated.

I'll have a look at the Betfair API.