Uncertainty Quantification for LLMs through Minimum Bayes Risk: Bridging Confidence and Consistency

Fuente: arXiv
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Auteurs principaux: Vashurin, Roman, Goloburda, Maiya, Ilina, Albina, Rubashevskii, Aleksandr, Nakov, Preslav, Shelmanov, Artem, Panov, Maxim
Format: Preprint
Publié: 2025
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author Vashurin, Roman
Goloburda, Maiya
Ilina, Albina
Rubashevskii, Aleksandr
Nakov, Preslav
Shelmanov, Artem
Panov, Maxim
author_facet Vashurin, Roman
Goloburda, Maiya
Ilina, Albina
Rubashevskii, Aleksandr
Nakov, Preslav
Shelmanov, Artem
Panov, Maxim
contents Uncertainty quantification (UQ) methods for Large Language Models (LLMs) encompass a variety of approaches, with two major types being particularly prominent: information-based, which focus on model confidence expressed as token probabilities, and consistency-based, which assess the semantic relationship between multiple outputs generated using repeated sampling. Several recent methods have combined these two approaches to boost UQ performance. However, they sometimes fail to outperform much simpler baseline methods. Our work discusses the fundamental approach to constructing uncertainty measures that directly links uncertainty with the minimum Bayes risks achieved by LLM decoding. Building on these findings, we propose a novel approach to integrating model confidence with output consistency, resulting in a family of efficient and robust UQ methods. Our investigation reveals distinctive characteristics of LLMs as probabilistic models, which help to explain why these UQ methods underperform in certain tasks. Based on these findings, we propose a new way of synthesizing model confidence and output consistency, leading to a family of efficient and robust UQ methods. We evaluate our approach across various tasks such as question answering, abstractive summarization, and machine translation, demonstrating sizable improvements over state-of-the-art UQ approaches.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04964
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Uncertainty Quantification for LLMs through Minimum Bayes Risk: Bridging Confidence and Consistency
Vashurin, Roman
Goloburda, Maiya
Ilina, Albina
Rubashevskii, Aleksandr
Nakov, Preslav
Shelmanov, Artem
Panov, Maxim
Computation and Language
Uncertainty quantification (UQ) methods for Large Language Models (LLMs) encompass a variety of approaches, with two major types being particularly prominent: information-based, which focus on model confidence expressed as token probabilities, and consistency-based, which assess the semantic relationship between multiple outputs generated using repeated sampling. Several recent methods have combined these two approaches to boost UQ performance. However, they sometimes fail to outperform much simpler baseline methods. Our work discusses the fundamental approach to constructing uncertainty measures that directly links uncertainty with the minimum Bayes risks achieved by LLM decoding. Building on these findings, we propose a novel approach to integrating model confidence with output consistency, resulting in a family of efficient and robust UQ methods. Our investigation reveals distinctive characteristics of LLMs as probabilistic models, which help to explain why these UQ methods underperform in certain tasks. Based on these findings, we propose a new way of synthesizing model confidence and output consistency, leading to a family of efficient and robust UQ methods. We evaluate our approach across various tasks such as question answering, abstractive summarization, and machine translation, demonstrating sizable improvements over state-of-the-art UQ approaches.
title Uncertainty Quantification for LLMs through Minimum Bayes Risk: Bridging Confidence and Consistency
topic Computation and Language
url https://arxiv.org/abs/2502.04964