How useful is yield as a performance measure?

There are many variables to measure the success of a betting system.  These range from the simple ’strike rate’ showing the percentage of bets won to ‘yield’ which, by incorporating the potential loss on a bet, includes some measure of risk.  It goes without saying that the longer a system has been in place and the more bets it has covered the more reliable it is in terms of predicting future results.   However given the same number of bets, a system with a high yield is not necessarily better than a system with a lower yield.  Betting against Derby is a low yielding bet since the risk of loss is low.  However if such bets offer positive value (i.e. net profit over time) and we exclude them simply because they are low yield we are giving up potential profits.

Continued