When LLMs Disagree: Diagnosing Relevance Filtering Bias and Retrieval Divergence in SDG Search

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Autori principali: Ingram, William A., Banerjee, Bipasha, Fox, Edward A.
Natura: Preprint
Pubblicazione: 2025
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author Ingram, William A.
Banerjee, Bipasha
Fox, Edward A.
author_facet Ingram, William A.
Banerjee, Bipasha
Fox, Edward A.
contents Large language models (LLMs) are increasingly used to assign document relevance labels in information retrieval pipelines, especially in domains lacking human-labeled data. However, different models often disagree on borderline cases, raising concerns about how such disagreement affects downstream retrieval. This study examines labeling disagreement between two open-weight LLMs, LLaMA and Qwen, on a corpus of scholarly abstracts related to Sustainable Development Goals (SDGs) 1, 3, and 7. We isolate disagreement subsets and examine their lexical properties, rank-order behavior, and classification predictability. Our results show that model disagreement is systematic, not random: disagreement cases exhibit consistent lexical patterns, produce divergent top-ranked outputs under shared scoring functions, and are distinguishable with AUCs above 0.74 using simple classifiers. These findings suggest that LLM-based filtering introduces structured variability in document retrieval, even under controlled prompting and shared ranking logic. We propose using classification disagreement as an object of analysis in retrieval evaluation, particularly in policy-relevant or thematic search tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2507_02139
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle When LLMs Disagree: Diagnosing Relevance Filtering Bias and Retrieval Divergence in SDG Search
Ingram, William A.
Banerjee, Bipasha
Fox, Edward A.
Information Retrieval
Artificial Intelligence
Digital Libraries
Large language models (LLMs) are increasingly used to assign document relevance labels in information retrieval pipelines, especially in domains lacking human-labeled data. However, different models often disagree on borderline cases, raising concerns about how such disagreement affects downstream retrieval. This study examines labeling disagreement between two open-weight LLMs, LLaMA and Qwen, on a corpus of scholarly abstracts related to Sustainable Development Goals (SDGs) 1, 3, and 7. We isolate disagreement subsets and examine their lexical properties, rank-order behavior, and classification predictability. Our results show that model disagreement is systematic, not random: disagreement cases exhibit consistent lexical patterns, produce divergent top-ranked outputs under shared scoring functions, and are distinguishable with AUCs above 0.74 using simple classifiers. These findings suggest that LLM-based filtering introduces structured variability in document retrieval, even under controlled prompting and shared ranking logic. We propose using classification disagreement as an object of analysis in retrieval evaluation, particularly in policy-relevant or thematic search tasks.
title When LLMs Disagree: Diagnosing Relevance Filtering Bias and Retrieval Divergence in SDG Search
topic Information Retrieval
Artificial Intelligence
Digital Libraries
url https://arxiv.org/abs/2507.02139