RBE

The Rank-Biased Entropy (RBE) of the top-k recommended articles is computed. This metric measures the diversity of topical mentions (e.g., entities or categories) among top-ranked recommendations, while applying position-based discounting using an exponential decay factor d.

Higher entropy indicates greater topical diversity in the list, particularly near the top ranks. The position-based weighting emphasizes early recommendations more heavily, aligning with the idea that users pay more attention to higher-ranked items.