“Play Calling Is About Probability, Not Certainty”

Take two traders who win 40 percent of the time with their winners being three times as large as their losers. One has a history of 1,000 trades and the other has a history of 10 trades. Who has a better chance in the next 10 trades to have only 10 percent of their total trades end up winners instead of the typical 40 percent? The one with the 10–trade history has the better chance. Why? The more trades in a history, the greater the probability of averages holding true. The fewer trades, the greater the probability of moving away from the average.

Consider a friend who receives a stock tip, makes some quick money, and tells everyone about it. There is a big problem with this scenario. His population of winning tips is extremely small–one to be exact. That’s statistically insignificant. He could just as easily follow his next hot tip and lose all of his money. One tip means nothing. The sample is essentially anecdotal evidence.

Thinking in terms of statistics is everywhere if you are observant. During a Monday Night Football game, one of the announcers, Ron Jaworski, put numbers and odds in perspective for playing the game of football: “Play calling is about probability, not certainty.”

It is the same in trend following trading.