Expectancy along with position sizing are probably the two most important factors in trading/investing success. Sadly most people have never even heard of the concept.
Expectancy is the average amount you can expect to win (or lose) per rupee at risk.
Here’s the formula for expectancy:
Expectancy = (Probability of Win * Average Win) – (Probability of Loss * Average Loss)
As an example let’s say that a trader has a system that produces winning trades 30% of the time. That trader’s average winning trade nets 10% while losing trades lose 3%.
Expectancy, position-sizing and other aspects of money management are far more important than discovering the holy grail entry system or indicator(s). Unfortunately entry techniques are where the vast majority of books and talking heads focus their attention. You could have the greatest stock picking system in the world but unless you take these money management issue into consideration you may not have any money left to trade the system. Having a system that gives you a positive expectancy should be in the forefront of your mind when putting together a trading plan.