Equation 2 · Part 1 · Measuring What a RAG System Retrieves, Not Just What It Answers
Symbol k
What this part means
k is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
k is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol k→Article meaning
The passage around this formula
A retrieval metric is computed from three things only: a query, a ranked list of documents or passages returned for it, and a set of relevance judgements — a labelled mapping from each query to the documents that count as relevant, usually built by human assessors ahead of time. None of the three requires a generator. This is the methodological point worth holding onto before any of the specific metrics: recall at k , precision at k , mean reciprocal rank and normalised discounted cumulative gain are all properties of a ranking function evaluated against ground truth, and they can be computed the moment the retriever returns its list, with no language model ever invoked.
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the article section
- [3] The TREC-8 Question Answering Track Report ↗
- [2] BEIR: A Heterogeneous Benchmark for Zero-shot Evaluation of Information Retrieval Models ↗
These citations provide research context; check each source for the exact claim it supports.