Sample size

The Math of an Edge

How many trades before you know anything

Ten trades tell you almost nothing. Thirty start to hint. A hundred, taken the same way, is where a win rate begins to mean something. Most beginners judge a strategy on a handful of trades, conclude it is broken, switch to a new one, and repeat forever — collecting tiny samples of many systems instead of a real sample of one. The discipline is to define the strategy, take it enough times to have data, and only then judge it.