Mat, I had a similar idea years ago when I used to burn the midnight oil with Qbasic , now with spreadsheets and databases easier to use I cannot see why you could not create something that would be useful.
In a lot of papers and online you can find ratings for all the races, these I suspect are generated by a program of one type or another, but when I was playing around I found some papers throw more weight at speed figures etc, where others tended to have a more form reading type view, going / course etc, wish I could remember who done what but it was years ago. :D, could do no worse than anaylise those already generated by these sources.
As to what you req is another matter, whatever you do, you will never see the horses in the paddock, how they ran last time (race watchers get it wrong as well), how they are at home, plus many many more of the things that come into why they run well or badly.
Football, now there's another thing, anyone ever looked at the weather aspect in football matches where it's raining / windy etc, to see if there is a trend or two to consider High / Low scores ??
The minute you start talking about what you're going to do if you lose, you have lost.
Got to update this when I have time please be patient ,thank you ,Open Forum...Total Lays......?Total Backs....?Hidden Forum Total Backs....?Total Lays......?