Strategy Backtester · Intermediate
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Hit Rate vs. Average Win/Loss
Win rate is the most over-weighted number in trading. What matters is expectancy — and a low win rate can have plenty of it.
The expectancy formula
Per-trade expectancy = (hit rate × average win) − (loss rate × average loss). A rule that wins just 40% of the time is profitable if its average winner is twice its average loser. Conversely, an 80% win rate bleeds money if the occasional loss is five times the typical gain.
Why trend rules win small-often-lose-rarely’s opposite
Trend-following rules often post low hit rates with large average wins; mean-reversion rules often post high hit rates with the risk of a rare large loss. Neither is “better” — the backtester lets you see which profile a rule actually has before you trade it.
Sample size matters
Ten trades prove nothing. Treat expectancy from a small trade count as a hint, not a verdict, and prefer rules with enough history to be believable.
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Educational content from Nations Indexes. Backtests are descriptive of historical data and are not investment advice or a promise of future results.