“Trading is a matter of probabilities. Any trading strategy, no matter how effective, will be wrong a certain percentage of the time. Traders often confuse the concepts of winning and losing traders with good and bad trades. A good trade can lose money, and a bad trade can make money. A good trade follows a process that will be profitable (at an acceptable risk) if repeated multiple times, although it can lose money on any individual trade. A bad trade follows a process that will lose money if repeated multiple times, but may make money on any individual trade.”
Jack D. Schwager, Autor der Market Wizards-Serie