ranking metrics

Ranking metrics evaluate how well a system arranges items based on relevance or importance, such as search results or recommendations. Common metrics include precision, which measures how many of the top items are relevant; recall, which assesses how many relevant items are included; and NDCG (Normalized Discounted Cumulative Gain), which considers both relevance and the order of items—giving higher importance to top-ranked results. These metrics help assess and improve the effectiveness of search engines and recommendation systems by providing clear, quantifiable insights into their performance.