Chris Collins

Tagged “ndcg”

Exploration ·

How web search works

Follow a query from the box you type it into to the ten blue links: how text becomes terms, how an inverted index stores and compresses them, how BM25 scores a match, how we know a ranking is any good, and how the whole thing is split across thousands of machines — with the tools running live between the paragraphs.

Search and retrieval

Tool ·

Ranking metrics workbench

Paste TREC qrels and runs (or CSV) and get P@k, recall@k, MAP, MRR, nDCG@k with linear and exponential gain, ERR and R-precision per query — checked against trec_eval and gdeval — then compare two rankers with paired t, Wilcoxon, randomisation and bootstrap tests, and simulate team-draft interleaving.

Search and retrieval