Equation 7 · 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 q
q is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
subscript
The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.
How to interpret it
Read this expression with the definitions, units, and assumptions supplied by the article.
What the article says around this equation
averaged over a query set Q , where is the position of the first relevant result for query q . Mean reciprocal rank was formalised as the primary scoring metric for the TREC-8 Question Answering track, the first large-scale evaluation of domain-independent question answering systems, where it assigned a value of 1/r to a ranked list of candidate answers based on the rank r of the one judged correct [ 3 ] . It rewards getting the single most useful passage near the top and is blind to everything else in the list, which is exactly the property a downstream generator that reads only the first few passages needs measured.
Sources cited in the surrounding passage
These citations give research context. Read each source to check which claims it supports.
Return to Measuring What a RAG System Retrieves, Not Just What It Answers