When an LLM is apprehensive about its answers -- and when its uncertainty is justified

Fuente: arXiv
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Autores principales: Sychev, Petr, Goncharov, Andrey, Vyazhev, Daniil, Khalafyan, Edvard, Zaytsev, Alexey
Formato: Preprint
Publicado: 2025
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author Sychev, Petr
Goncharov, Andrey
Vyazhev, Daniil
Khalafyan, Edvard
Zaytsev, Alexey
author_facet Sychev, Petr
Goncharov, Andrey
Vyazhev, Daniil
Khalafyan, Edvard
Zaytsev, Alexey
contents Uncertainty estimation is crucial for evaluating Large Language Models (LLMs), particularly in high-stakes domains where incorrect answers result in significant consequences. Numerous approaches consider this problem, while focusing on a specific type of uncertainty, ignoring others. We investigate what estimates, specifically token-wise entropy and model-as-judge (MASJ), would work for multiple-choice question-answering tasks for different question topics. Our experiments consider three LLMs: Phi-4, Mistral, and Qwen of different sizes from 1.5B to 72B and $14$ topics. While MASJ performs similarly to a random error predictor, the response entropy predicts model error in knowledge-dependent domains and serves as an effective indicator of question difficulty: for biology ROC AUC is $0.73$. This correlation vanishes for the reasoning-dependent domain: for math questions ROC-AUC is $0.55$. More principally, we found out that the entropy measure required a reasoning amount. Thus, data-uncertainty related entropy should be integrated within uncertainty estimates frameworks, while MASJ requires refinement. Moreover, existing MMLU-Pro samples are biased, and should balance required amount of reasoning for different subdomains to provide a more fair assessment of LLMs performance.
format Preprint
id arxiv_https___arxiv_org_abs_2503_01688
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle When an LLM is apprehensive about its answers -- and when its uncertainty is justified
Sychev, Petr
Goncharov, Andrey
Vyazhev, Daniil
Khalafyan, Edvard
Zaytsev, Alexey
Computation and Language
Machine Learning
Uncertainty estimation is crucial for evaluating Large Language Models (LLMs), particularly in high-stakes domains where incorrect answers result in significant consequences. Numerous approaches consider this problem, while focusing on a specific type of uncertainty, ignoring others. We investigate what estimates, specifically token-wise entropy and model-as-judge (MASJ), would work for multiple-choice question-answering tasks for different question topics. Our experiments consider three LLMs: Phi-4, Mistral, and Qwen of different sizes from 1.5B to 72B and $14$ topics. While MASJ performs similarly to a random error predictor, the response entropy predicts model error in knowledge-dependent domains and serves as an effective indicator of question difficulty: for biology ROC AUC is $0.73$. This correlation vanishes for the reasoning-dependent domain: for math questions ROC-AUC is $0.55$. More principally, we found out that the entropy measure required a reasoning amount. Thus, data-uncertainty related entropy should be integrated within uncertainty estimates frameworks, while MASJ requires refinement. Moreover, existing MMLU-Pro samples are biased, and should balance required amount of reasoning for different subdomains to provide a more fair assessment of LLMs performance.
title When an LLM is apprehensive about its answers -- and when its uncertainty is justified
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2503.01688