Uncertainty-Aware Fusion: An Ensemble Framework for Mitigating Hallucinations in Large Language Models

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Main Authors: Dey, Prasenjit, Merugu, Srujana, Kaveri, Sivaramakrishnan
Format: Preprint
Published: 2025
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author Dey, Prasenjit
Merugu, Srujana
Kaveri, Sivaramakrishnan
author_facet Dey, Prasenjit
Merugu, Srujana
Kaveri, Sivaramakrishnan
contents Large Language Models (LLMs) are known to hallucinate and generate non-factual outputs which can undermine user trust. Traditional methods to directly mitigate hallucinations, such as representation editing and contrastive decoding, often require additional training data and involve high implementation complexity. While ensemble-based approaches harness multiple LLMs to tap into the "wisdom of crowds", these methods overlook uncertainties in individual model responses. Recent studies reveal that uncertainty estimation can enable LLMs to self-assess the likelihood of generating hallucinations. In this work, we focus on factoid question answering (QA) and observe that LLMs accuracy and self-assessment capabilities vary widely with different models excelling in different scenarios. Leveraging this insight, we propose Uncertainty-Aware Fusion (UAF), an ensemble framework to reduces hallucinations by strategically combining multiple LLM based on their accuracy and self-assessment abilities. Empirical results on several public benchmark datasets show that UAF outperforms state-of-the-art hallucination mitigation methods by $8\%$ in factual accuracy, while either narrowing or surpassing the performance gap with GPT-4.
format Preprint
id arxiv_https___arxiv_org_abs_2503_05757
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Uncertainty-Aware Fusion: An Ensemble Framework for Mitigating Hallucinations in Large Language Models
Dey, Prasenjit
Merugu, Srujana
Kaveri, Sivaramakrishnan
Machine Learning
Artificial Intelligence
Computation and Language
Large Language Models (LLMs) are known to hallucinate and generate non-factual outputs which can undermine user trust. Traditional methods to directly mitigate hallucinations, such as representation editing and contrastive decoding, often require additional training data and involve high implementation complexity. While ensemble-based approaches harness multiple LLMs to tap into the "wisdom of crowds", these methods overlook uncertainties in individual model responses. Recent studies reveal that uncertainty estimation can enable LLMs to self-assess the likelihood of generating hallucinations. In this work, we focus on factoid question answering (QA) and observe that LLMs accuracy and self-assessment capabilities vary widely with different models excelling in different scenarios. Leveraging this insight, we propose Uncertainty-Aware Fusion (UAF), an ensemble framework to reduces hallucinations by strategically combining multiple LLM based on their accuracy and self-assessment abilities. Empirical results on several public benchmark datasets show that UAF outperforms state-of-the-art hallucination mitigation methods by $8\%$ in factual accuracy, while either narrowing or surpassing the performance gap with GPT-4.
title Uncertainty-Aware Fusion: An Ensemble Framework for Mitigating Hallucinations in Large Language Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2503.05757