How to read an expectancy
Expectancy combines hit rate with the size of the wins and losses into a single number: the average profit per trade.
Positive expectancy means the strategy makes money as the trade count grows. Negative expectancy means it loses money, and no winning streak changes that; it only delays it.
What breaks expectancy
Averages hide their own tails. One resolved market that returned 20 times the stake can drag average win high enough to make a losing strategy read positive. Check expectancy against the median trade, or against the same figure with the largest result removed.
Expectancy also assumes stable position sizing. If a trader sized up ten times on a handful of trades, per-trade expectancy no longer describes what happened to the account. Read it with cumulative P&L and drawdown.
Where 0xinsider uses expectancy
Rolling expectancy is one of the series on trader profiles, so the question is not whether it is positive today but whether it has stayed positive across windows as more markets resolved.
