Feature Validation

A feature with IC of 0.05 on the full sample may have IC of 0.12 in one year and -0.03 in every other year. Without validation, the model trains on noise disguised as signal.

The Problem

Skipping feature validation leads to three failures: lookahead contamination, regime-specific features that fail live, and redundant features that waste model capacity.

The Pattern

WRONG

from sklearn.ensemble import GradientBoostingRegressor

# Train on all features without any validation - overfitting guaranteed
model = GradientBoostingRegressor(n_estimators=200)
model.fit(X_train, y_train)  # 50 features, no idea which are noise