One Permutation Is All You Need: Fast, Deterministic Feature Importance and Model Stress-Testing
The authors replace multiple random feature permutations with a single, mathematically optimal deterministic permutation to estimate variable importance. This new method is faster, more stable, and reproducible than classical permutation methods. It provides a unified framework for explaining model behavior and assessing systemic risk by combining Direct Variable Importance (DVI) and Systemic Variable Importance (SVI).