What the numbers mean, and where they mislead you.
Recovering from a 50% loss takes a 100% gain. What drawdown is, and why you should read it before the return figure.
Up 50% then down 50% leaves you at −25%, not flat. The compounding illusion and how to read annualised return.
Overfitting, look-ahead bias, survivorship, execution costs and regime dependence. What to verify before you trust a result.