The Anatomy of Uncertainty in LLMs

Fuente: arXiv
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Hauptverfasser: Taparia, Aditya, Senanayake, Ransalu, Thopalli, Kowshik, Narayanaswamy, Vivek
Format: Preprint
Veröffentlicht: 2026
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author Taparia, Aditya
Senanayake, Ransalu
Thopalli, Kowshik
Narayanaswamy, Vivek
author_facet Taparia, Aditya
Senanayake, Ransalu
Thopalli, Kowshik
Narayanaswamy, Vivek
contents Understanding why a large language model (LLM) is uncertain about the response is important for their reliable deployment. Current approaches, which either provide a single uncertainty score or rely on the classical aleatoric-epistemic dichotomy, fail to offer actionable insights for improving the generative model. Recent studies have also shown that such methods are not enough for understanding uncertainty in LLMs. In this work, we advocate for an uncertainty decomposition framework that dissects LLM uncertainty into three distinct semantic components: (i) input ambiguity, arising from ambiguous prompts; (ii) knowledge gaps, caused by insufficient parametric evidence; and (iii) decoding randomness, stemming from stochastic sampling. Through a series of experiments we demonstrate that the dominance of these components can shift across model size and task. Our framework provides a better understanding to audit LLM reliability and detect hallucinations, paving the way for targeted interventions and more trustworthy systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24967
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Anatomy of Uncertainty in LLMs
Taparia, Aditya
Senanayake, Ransalu
Thopalli, Kowshik
Narayanaswamy, Vivek
Artificial Intelligence
Understanding why a large language model (LLM) is uncertain about the response is important for their reliable deployment. Current approaches, which either provide a single uncertainty score or rely on the classical aleatoric-epistemic dichotomy, fail to offer actionable insights for improving the generative model. Recent studies have also shown that such methods are not enough for understanding uncertainty in LLMs. In this work, we advocate for an uncertainty decomposition framework that dissects LLM uncertainty into three distinct semantic components: (i) input ambiguity, arising from ambiguous prompts; (ii) knowledge gaps, caused by insufficient parametric evidence; and (iii) decoding randomness, stemming from stochastic sampling. Through a series of experiments we demonstrate that the dominance of these components can shift across model size and task. Our framework provides a better understanding to audit LLM reliability and detect hallucinations, paving the way for targeted interventions and more trustworthy systems.
title The Anatomy of Uncertainty in LLMs
topic Artificial Intelligence
url https://arxiv.org/abs/2603.24967