This is a bit off topic but.... A formal approach to risking the optimal amount of your betting bank on each race is in principle quite simple and involves creating your own tissue prices on the runners in the race (or your estimate of the probability of each horse winning) and comparing them with the prices available in the betting industry. You can then estimate the percentage of your betting bank that you should wager by multiplying the odds available on the horse with the probability that the horse will win minus the probability that the horse will lose, and divide the number by the odds available on the horse. So, for example, if a race has three horses A (evens), B (2/1) and C (5/1), and you price up the race as A (evens), B (3/1) and C (3/1). Your assessment is that the chance of each horse to win is A = 50%, B = 25% and C = 25%. Then you will obviously want to bet on C as this horse is available at a better price than your assessment of the race, and to calculate the percentage of your betting bank to stake you multiply the odds available (5) by the probability that the horse will win (0.25) minus the probability that the horse will lose (0.75) and divide by the odds available (5). (5*0.25-0.75)/5 = 0.10 = 10% of your betting bank. This is known as the kelly criterion and will give the optimal percentage of your betting bank to stake in win/lose bets when there is no additional charges (such as the commission on the exchanges). Very complicated modifications of the equation can take account of other factors like this. This strategy is also dependent on the punter accurately assessing the probability of each horse winning, and further modifications have been developed to include an assessment of the degree of certainty that the punter has in his tissue prices. Making these calculations may seem alien to most casual punters, but certainly the sophisticated computer algorithms designed to help professional punters assess bets will incorporate these calculations.
