Bill Benter: No Guarantees

…it is difficult to know how great an edge can be achieved at a particular track until one develops a model for that track and tests it, which requires considerable effort. Should that prove successful, there is still no guarantee that the future will be as profitable as past simulations might indicate. The public may become more skillful, or the dishonesty of the races may increase, or another computer handicapper may start playing at the same time.

William Benter, “Computer Based Horse Race Handicapping and Wagering Systems: A Report”