A feature interaction occurs when one feature’s relationship with an outlier score changes according to another feature’s value. A global importance ranking can hide this dependency. section 13.2.1
Height and length in abalone data
Height may relate differently to an outlier score at different lengths. Replacing the original variables with an interpretable ratio such as height divided by length can expose the dependency; proxy models offer another route. section 13.2.1
Feature importance estimates provide useful context but do not readily reveal interactions. SHAP is preferred where possible, while approximate alternatives may misorder or equalize feature contributions. section 13.2.1



