Equation 4 · Measuring What a RAG System Retrieves, Not Just What It Answers
What does this equation mean?
Read the formula alongside the article passage below. Each part has a deeper page with its role in the equation, the supporting passage and nearby citations.
This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.
Read it piece by piece
Symbol k
k is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
How to interpret it
Read this expression with the definitions, units, and assumptions supplied by the article.
What the article says around this equation
Recall at k is the simplest of the four: the fraction of relevant documents that appear anywhere in the top k results. It answers one question only — did the evidence make it into the candidate set at all — and says nothing about where within that set it landed. Mean reciprocal rank answers the positional question for the single best hit:
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 give research context. Read each source to check which claims it supports.
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