URAG: A Benchmark for Uncertainty Quantification in Retrieval-Augmented Large Language Models

Fuente: arXiv
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Autores principales: Nguyen, Vinh, Dang, Cuong, Zhang, Jiahao, Tran, Hoa, Tran, Minh, Chau, Trinh, Le, Thai, Cheng, Lu, Wang, Suhang
Formato: Preprint
Publicado: 2026
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author Nguyen, Vinh
Dang, Cuong
Zhang, Jiahao
Tran, Hoa
Tran, Minh
Chau, Trinh
Le, Thai
Cheng, Lu
Wang, Suhang
author_facet Nguyen, Vinh
Dang, Cuong
Zhang, Jiahao
Tran, Hoa
Tran, Minh
Chau, Trinh
Le, Thai
Cheng, Lu
Wang, Suhang
contents Retrieval-Augmented Generation (RAG) has emerged as a widely adopted approach for enhancing LLMs in scenarios that demand extensive factual knowledge. However, current RAG evaluations concentrate primarily on correctness, which may not fully capture the impact of retrieval on LLM uncertainty and reliability. To bridge this gap, we introduce URAG, a comprehensive benchmark designed to assess the uncertainty of RAG systems across various fields like healthcare, programming, science, math, and general text. By reformulating open-ended generation tasks into multiple-choice question answering, URAG allows for principled uncertainty quantification via conformal prediction. We apply the evaluation pipeline to 8 standard RAG methods, measuring their performance through both accuracy and prediction-set sizes based on LAC and APS metrics. Our analysis shows that (1) accuracy gains often coincide with reduced uncertainty, but this relationship breaks under retrieval noise; (2) simple modular RAG methods tend to offer better accuracy-uncertainty trade-offs than more complex reasoning pipelines; and (3) no single RAG approach is universally reliable across domains. We further show that (4) retrieval depth, parametric knowledge dependence, and exposure to confidence cues can amplify confident errors and hallucinations. Ultimately, URAG establishes a systematic benchmark for analyzing and enhancing the trustworthiness of retrieval-augmented systems. Our code is available on GitHub.
format Preprint
id arxiv_https___arxiv_org_abs_2603_19281
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle URAG: A Benchmark for Uncertainty Quantification in Retrieval-Augmented Large Language Models
Nguyen, Vinh
Dang, Cuong
Zhang, Jiahao
Tran, Hoa
Tran, Minh
Chau, Trinh
Le, Thai
Cheng, Lu
Wang, Suhang
Computation and Language
Artificial Intelligence
Information Retrieval
Retrieval-Augmented Generation (RAG) has emerged as a widely adopted approach for enhancing LLMs in scenarios that demand extensive factual knowledge. However, current RAG evaluations concentrate primarily on correctness, which may not fully capture the impact of retrieval on LLM uncertainty and reliability. To bridge this gap, we introduce URAG, a comprehensive benchmark designed to assess the uncertainty of RAG systems across various fields like healthcare, programming, science, math, and general text. By reformulating open-ended generation tasks into multiple-choice question answering, URAG allows for principled uncertainty quantification via conformal prediction. We apply the evaluation pipeline to 8 standard RAG methods, measuring their performance through both accuracy and prediction-set sizes based on LAC and APS metrics. Our analysis shows that (1) accuracy gains often coincide with reduced uncertainty, but this relationship breaks under retrieval noise; (2) simple modular RAG methods tend to offer better accuracy-uncertainty trade-offs than more complex reasoning pipelines; and (3) no single RAG approach is universally reliable across domains. We further show that (4) retrieval depth, parametric knowledge dependence, and exposure to confidence cues can amplify confident errors and hallucinations. Ultimately, URAG establishes a systematic benchmark for analyzing and enhancing the trustworthiness of retrieval-augmented systems. Our code is available on GitHub.
title URAG: A Benchmark for Uncertainty Quantification in Retrieval-Augmented Large Language Models
topic Computation and Language
Artificial Intelligence
Information Retrieval
url https://arxiv.org/abs/2603.19281