Horseracebase

Sporting,

They are calculated by an algorythm which includes everything, jockey trainer weight and the last 10 races of form. You can tweek the weightings of each component yourself then run the resukting algorytm against past races as a back test.

The database is extremely fast as its held by chris at HRB. He is a hard working approachable dedicated chap. Ask for a free trial when you have spare time and give it a go.

Its excellent for creating systems as it has masses of variables including valuable oneslike PHB

decent site, bit dated but excellent data/stats/etc etc...
imo
i think there ratings are ai generated on all above

Thanks for the reply Celtic, I have previously subscribed but I just couldn`t get to grips with the ratings, one thing I noticed is, the top rated are usually last time out winners but horses dropping in the weights because of recent poor form would generally be rated near the bottom of the ratings, the problem with this method is lots of well handicapped horses are overlooked if using the ratings as a starting point, is there a way of changing this ?

Yes just adjust the weightings for the performances to give higher weighting for less recent runnings then back test.

The other way is to create a system comparing todays OR with the best previous winning OR