Articles

Introduction In this article we'll take a look at two related practices that are widely used by traders called Backtesting and Data Mining. These are techniques that are powerful and valuable if we use them correctly, however traders often misuse them. Therefore, we'll also explore two common pitfalls of these techniques, known as the multiple hypothesis problem and overfitting and how to overcome these pitfalls. Backtesting Backtesting is just the process of using historical data to test the performance of some trading strategy. Backtesting generally starts with a strategy that we would like to test, for instance buying GBP/USD when it crosses above the 20-day moving average and selling when it crosses below that average. Now we could...

I get more questions about stop losses than about any other subject. Clearly this strategy causes traders a lot of pain and confusion. Some of it stems from the schizoid nature of our modern markets. But most of it reflects an underlying weakness in trade management skills. What takes place at the end of a trade usually reflects decisions made at the beginning. In other words, the best entries usually lead to the most profitable exits. This is the most urgent wisdom I can give when it comes to stop-loss placement. We can spend hours deciding whether a stock is a good buy or a good sell, but this emphasis is often misplaced. Over time, carefully chosen exits are more important than great entries. You don't believe me? Just ask all...