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Main Authors: Klearman, Andrew, Revutchi, Radu, Garg, Rohin, Chakravarti, Rishav, Denton, Samuel Marc, Xue, Yuan
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.20763
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_version_ 1866908987268530176
author Klearman, Andrew
Revutchi, Radu
Garg, Rohin
Chakravarti, Rishav
Denton, Samuel Marc
Xue, Yuan
author_facet Klearman, Andrew
Revutchi, Radu
Garg, Rohin
Chakravarti, Rishav
Denton, Samuel Marc
Xue, Yuan
contents Retrieval quality is the primary bottleneck for accuracy and robustness in retrieval-augmented generation (RAG). Current evaluation relies on heuristically constructed query sets, which introduce a hidden intrinsic bias. We formalize retrieval evaluation as a statistical estimation problem, showing that metric reliability is fundamentally limited by the evaluation-set construction. We further introduce \emph{semantic stratification}, which grounds evaluation in corpus structure by organizing documents into an interpretable global space of entity-based clusters and systematically generating queries for missing strata. This yields (1) formal semantic coverage guarantees across retrieval regimes and (2) interpretable visibility into retrieval failure modes. Experiments across multiple benchmarks and retrieval methods validate our framework. The results expose systematic coverage gaps, identify structural signals that explain variance in retrieval performance, and show that stratified evaluation yields more stable and transparent assessments while supporting more trustworthy decision-making than aggregate metrics.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20763
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Coverage, Not Averages: Semantic Stratification for Trustworthy Retrieval Evaluation
Klearman, Andrew
Revutchi, Radu
Garg, Rohin
Chakravarti, Rishav
Denton, Samuel Marc
Xue, Yuan
Information Retrieval
Artificial Intelligence
Machine Learning
Retrieval quality is the primary bottleneck for accuracy and robustness in retrieval-augmented generation (RAG). Current evaluation relies on heuristically constructed query sets, which introduce a hidden intrinsic bias. We formalize retrieval evaluation as a statistical estimation problem, showing that metric reliability is fundamentally limited by the evaluation-set construction. We further introduce \emph{semantic stratification}, which grounds evaluation in corpus structure by organizing documents into an interpretable global space of entity-based clusters and systematically generating queries for missing strata. This yields (1) formal semantic coverage guarantees across retrieval regimes and (2) interpretable visibility into retrieval failure modes. Experiments across multiple benchmarks and retrieval methods validate our framework. The results expose systematic coverage gaps, identify structural signals that explain variance in retrieval performance, and show that stratified evaluation yields more stable and transparent assessments while supporting more trustworthy decision-making than aggregate metrics.
title Coverage, Not Averages: Semantic Stratification for Trustworthy Retrieval Evaluation
topic Information Retrieval
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2604.20763