Catalog Coverage#
The share of the item catalog that ever gets recommended.
Important
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What it is#
Catalog coverage is the proportion of the entire item catalog that a recommender actually surfaces to users — the share of products that ever appear in someone’s recommendations. It measures the breadth of the system’s reach, not the quality of any one list.
The formula#
computed as an aggregate over all users and a time window (often expressed as a percentage).
Why it matters#
Low coverage signals popularity bias — the system funnels everyone toward the same few hits, starving the long tail and neglecting niche tastes; high coverage means diverse, inclusive recommendations. Because recommending popular items is often accurate but narrow, coverage is reported alongside accuracy — a good system scores well on both.
Theme: Recommender Systems · All terminology
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Mind map — connected ideas
Item Coverage · User Coverage · Long-Tail Items · Intra-List Diversity (ILD) · Diminishing Utility · Relevance in Recommender Systems
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More in Recommender Systems
Cosine Similarity of Item Features · Diminishing Utility · Diversity (in Recommender Systems) · Dominating in Recommender Systems · Genre Overlap · Hit Rate (HR) · Intra-List Diversity (ILD) · Item Coverage · Jaccard index · Novelty (in Recommender Systems) · Relevance in Recommender Systems · Self-Information of Popularity · User Coverage
See also
Source article Adapted (context, re-expressed) in our own words from: Catalog Coverage (insightful-data-lab.com).