Imagine you notice that the price of crude oil for delivery in June and the price for delivery in December usually move together, but occasionally they drift apart. If you buy the cheap one and sell the expensive one, betting they will come back together, you are doing statistical arbitrage. This chapter shows you how to turn that intuition into a disciplined, data‑driven trading strategy, while avoiding the hidden traps that turn a promising backtest into a real‑world money loser.