Trading Expectancy
Expectancy describes the average expected outcome per trade based on historical wins, losses and their average sizes.
Why expectancy is useful
It combines win probability and payoff into a single historical measure instead of looking at win rate alone.
Positive and negative expectancy
Positive historical expectancy means the average trade outcome was above zero over the reviewed sample; negative expectancy means the opposite.
Sample size still matters
A small number of trades can make expectancy unstable, so the amount of available evidence matters when interpreting it.