Retrieval Augmented Question Answering: When Should LLMs Admit Ignorance?

Fuente: arXiv
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Main Authors: Wang, Dingmin, Ma, Ji, Kumar, Shankar
Format: Preprint
Published: 2025
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author Wang, Dingmin
Ma, Ji
Kumar, Shankar
author_facet Wang, Dingmin
Ma, Ji
Kumar, Shankar
contents The success of expanded context windows in Large Language Models (LLMs) has driven increased use of broader context in retrieval-augmented generation. We investigate the use of LLMs for retrieval augmented question answering. While longer contexts make it easier to incorporate targeted knowledge, they introduce more irrelevant information that hinders the model's generation process and degrades its performance. To address the issue, we design an adaptive prompting strategy which involves splitting the retrieved information into smaller chunks and sequentially prompting a LLM to answer the question using each chunk. Adjusting the chunk size allows a trade-off between incorporating relevant information and reducing irrelevant information. Experimental results on three open-domain question answering datasets demonstrate that the adaptive strategy matches the performance of standard prompting while using fewer tokens. Our analysis reveals that when encountering insufficient information, the LLM often generates incorrect answers instead of declining to respond, which constitutes a major source of error. This finding highlights the need for further research into enhancing LLMs' ability to effectively decline requests when faced with inadequate information.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23836
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Retrieval Augmented Question Answering: When Should LLMs Admit Ignorance?
Wang, Dingmin
Ma, Ji
Kumar, Shankar
Computation and Language
Artificial Intelligence
Machine Learning
The success of expanded context windows in Large Language Models (LLMs) has driven increased use of broader context in retrieval-augmented generation. We investigate the use of LLMs for retrieval augmented question answering. While longer contexts make it easier to incorporate targeted knowledge, they introduce more irrelevant information that hinders the model's generation process and degrades its performance. To address the issue, we design an adaptive prompting strategy which involves splitting the retrieved information into smaller chunks and sequentially prompting a LLM to answer the question using each chunk. Adjusting the chunk size allows a trade-off between incorporating relevant information and reducing irrelevant information. Experimental results on three open-domain question answering datasets demonstrate that the adaptive strategy matches the performance of standard prompting while using fewer tokens. Our analysis reveals that when encountering insufficient information, the LLM often generates incorrect answers instead of declining to respond, which constitutes a major source of error. This finding highlights the need for further research into enhancing LLMs' ability to effectively decline requests when faced with inadequate information.
title Retrieval Augmented Question Answering: When Should LLMs Admit Ignorance?
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2512.23836