Rule 1: Operate on handicap races only.
Rule 2: Consider only colts, horses and geldings.
Rule 3: Last start <=10 days.
Rule 4: Last win <=90 days.
Rule 5: Must be starting at under $11.

This system was from the Flatstats website www.flatstats.co.uk and which I have adopted to Australian conditions. The Flatstats website says the system works because males hold a tremendous edge over females, winning within a certain number of days shows winning ability and that single-figure SP ensures that a contender is no donkey or is not taking a big rise in class.