ranking

Definition

Ordering a set of candidates by predicted relevance, and the output format that results. It is evaluated differently from classification because position matters: metrics such as nDCG and MRR weight the top of the list far more heavily, reflecting that users rarely look past the first few results. The practical consequence is that a model with worse pointwise accuracy can be the better ranker, and vice versa.

Explainers using this term

• Recommenders and Embeddings — Same Math as RAG, Different GoalBPR: Bayesian Personalized Ranking from Implicit Feedback