Expectancy(Expectancy)
The average expected gain per trade: (win rate × avg. win) − (loss rate × avg. loss). Positive expectancy is the mathematical condition for long-term profitability.
Also written as: beklenti değeri · matematiksel beklenti
Example: 40% win rate, average win 2R, average loss 1R → 0.4×2 − 0.6×1 = +0.2R/trade. Over 100 trades, ~20R.
Expectancy is only meaningful over a sufficient number of trades and must be calculated with costs included. Trying to raise the win rate on its own (by widening the stop) can increase the average loss and lower expectancy.