Hard Negatives, Hard Lessons: Revisiting Training Data Quality for Robust Information Retrieval with LLMs

Nandan Thakur, Crystina Zhang, Xueguang Ma, Jimmy Lin


Abstract
Training robust retrieval and reranker models typically relies on large-scale retrieval datasets; for example, the BGE collection contains 1.6 million query-passage pairs sourced from various data sources.However, we find that certain datasets can negatively impact model effectiveness \textemdashpruning 8 out of 15 datasets from the BGE collection, reduces the training set size by 2.35×, surprisingly increases nDCG@10 on BEIR by 1.0 point.This motivates a deeper examination of training data quality, with a particular focus on “false negatives”, where relevant passages are incorrectly labeled as irrelevant.We utilize LLMs as a simple, cost-effective approach to *identify* and *relabel* false negatives in training datasets.Experimental results show that relabeling false negatives as true positives improves both E5 (base) and Qwen2.5-7B retrieval models by 0.7-1.4 points on BEIR and by 1.7-1.8 points at nDCG@10 on zero-shot AIR-Bench evaluation.Similar gains are observed for rerankers fine-tuned on the relabeled data, such as Qwen2.5-3B on BEIR.The reliability of LLMs to identify false negatives is supported by human annotation results. Our training dataset and code are publicly available.
Anthology ID:
2025.findings-emnlp.481
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2025
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
9064–9083
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URL:
https://aclanthology.org/2025.findings-emnlp.481/
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Cite (ACL):
Nandan Thakur, Crystina Zhang, Xueguang Ma, and Jimmy Lin. 2025. Hard Negatives, Hard Lessons: Revisiting Training Data Quality for Robust Information Retrieval with LLMs. In Findings of the Association for Computational Linguistics: EMNLP 2025, pages 9064–9083, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Hard Negatives, Hard Lessons: Revisiting Training Data Quality for Robust Information Retrieval with LLMs (Thakur et al., Findings 2025)
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https://aclanthology.org/2025.findings-emnlp.481.pdf
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