From an article:
http://www.lonestocktrader.com/make-money-trading-positive-expectancy/
The truth is that the very best traders out there are right only about 50% of the time or less: William O’Neil, Mark Minervini, Peter Brandt, Bill Lipschultz, Colm O’Shea, Ray Dalio, Bruce Kovner, etc…
Steven Cohen, one of the best stock traders out there who was also features in Stock Market Wizards and is mentoring traders said: “
My best trader makes money only 63% of the time. Most traders make money only in the 50% to 55% range. That means you’re going to be wrong a lot. If that’s the case, you better make sure your losses are as small as they can be, and that your winners are bigger.”
The Profit/Loss Ratio
If we can’t achieve a consistently high win rate and are doomed to be right about 50% or less of the time, the secret simply is to make more money when you are right, than lose money when you are wrong.
The profit/loss ratio is your average win to your average loss. And if over a sequence of trades, you, on average, make more money than you lose, you make money over time despite being right only 50% of the time. This is how professional traders make money consistently.
And as opposed to the win rate which is outside of your control, you have much more influence over your profit/loss ratio. Indeed, you can control how much you will lose on a trade by using stop losses. You are the one who decide to enter a new position at a certain price following a certain setup and you are the one who decide where to place your stop loss. If like all the successful traders, you keep a neat track record of your trades, you should know your average profit % and average loss %. Based on that, you can easily adjust your stop loss level and type of trades you take, and put yourself in a position to make much more money when you’re right, than lose when wrong.