Trading expectancy estimates what a process produces per trade over a large sample. It combines win rate with average win and average loss, so it is less misleading than a single headline number.
Why it matters
A strategy can win often but lose too much when wrong. Another can lose often but have larger winners. Expectancy helps you ask whether the relationship between those numbers makes sense.
Protect the sample
Do not mix every instrument, setup, and market regime into one number. Group comparable trades and record whether you followed the rules. A positive expectancy from planned trades does not justify impulsive trades.
Use it beside risk-reward ratio and a weekly journal review. The purpose is not false precision; it is a more honest view of the process.
