Walk-Forward Analysis
Protect against overfitting by testing strategy on out-of-sample data. Each fold optimizes on train period and tests on unseen test period.
How Walk-Forward Works
1. Data is split into multiple folds (e.g., 4 folds)
2. Each fold has a train period (e.g., 75%) and test period (e.g., 25%)
3. Strategy parameters are optimized on train data
4. Best parameters are tested on out-of-sample test data
5. Results are aggregated across all test periods
|------ Train 1 ------|-- Test 1 --|
|------ Train 2 ------|-- Test 2 --|
|------ Train 3 ------|-- Test 3 --|
|------ Train 4 ------|-- Test 4 --|
Understanding Results
- Efficiency Ratio: Test Sharpe / Train Sharpe. Values > 0.7 indicate good generalization.
- Parameter Stability: Low CV (< 0.3) means parameters are stable across folds.
- WF vs Naive: Walk-forward typically shows lower but more realistic performance.