Revisiting N2DCG: Empirical Reformulation for Carousel Recommendation

_reachsumit · x · 2026-08-25

The study identifies limitations in the standard N2DCG metric for carousel recommendations: its ideal ranking violates carousel constraints and its discount function mismatches user behavior. The authors propose a reformulation that normalizes by respecting constraints and uses an empirically grounded discount function. Validated with eye-tracking data, the new metric better reflects user behavior and predicts carousel layout comparisons.

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