What is Curve Fitting?

Curve Fitting
Forex Trading Glossary

Quick Answer: Curve fitting is over-optimizing a trading strategy to fit historical data, often producing poor real-world performance.

What is Curve Fitting?

Curve fitting is the practice of over-optimizing a strategy to perform well on historical data at the expense of future robustness. It is a common pitfall in algorithmic and discretionary trading.

Warning Signs

  • Too many parameters: Strategy relies on numerous optimized inputs.
  • Poor out-of-sample results: Performance collapses on unseen data.
  • Overreaction to noise: Strategy incorporates random quirks in historical prices.
  • Lack of rationale: No logical explanation for parameter choices.

Stay Objective

Split data into in-sample, out-of-sample, and live-forward tests. Reject systems that fail robustness checks.

Preventing Curve Fitting

  • Simplify rules: Use fewer parameters with clear logic.
  • Walk-forward testing: Recalibrate periodically on rolling windows.
  • Monte Carlo analysis: Stress-test results with random permutations.
  • Keep performance realistic: Avoid strategies that promise perfect equity curves.

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