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Main Authors: Recasens, Pol G., Gutierrez, Alberto, Torres, Jordi, Berral, Josep. Ll, Carnerero-Cano, Javier, Halimi, Anisa, Fraser, Kieran
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2506.09630
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author Recasens, Pol G.
Gutierrez, Alberto
Torres, Jordi
Berral, Josep. Ll
Carnerero-Cano, Javier
Halimi, Anisa
Fraser, Kieran
author_facet Recasens, Pol G.
Gutierrez, Alberto
Torres, Jordi
Berral, Josep. Ll
Carnerero-Cano, Javier
Halimi, Anisa
Fraser, Kieran
contents Large Language Models (LLMs) are increasingly used for synthetic tabular data generation through in-context learning (ICL), offering a practical solution for data augmentation in data scarce scenarios. While prior work has shown the potential of LLMs to improve downstream task performance through augmenting underrepresented groups, these benefits often assume access to a subset of unbiased in-context examples, representative of the real dataset. In real-world settings, however, data is frequently noisy and demographically skewed. In this paper, we systematically study how statistical biases within in-context examples propagate to the distribution of synthetic tabular data, showing that even mild in-context biases lead to global statistical distortions. We further introduce an adversarial scenario where a malicious contributor can inject bias into the synthetic dataset via a subset of in-context examples, ultimately compromising the fairness of downstream classifiers for a targeted and protected subgroup. Finally, we evaluate mitigation strategies based on preprocessing in-context examples, demonstrating that while such interventions can attenuate disparity, the inherent sensitivity of LLMs to adversarial prompts remains a persistent challenge. Our findings highlight a critical new vulnerability in LLM-based data generation pipelines within sensitive domains.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09630
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle In-Context Bias Propagation in LLM-Based Tabular Data Generation
Recasens, Pol G.
Gutierrez, Alberto
Torres, Jordi
Berral, Josep. Ll
Carnerero-Cano, Javier
Halimi, Anisa
Fraser, Kieran
Machine Learning
Large Language Models (LLMs) are increasingly used for synthetic tabular data generation through in-context learning (ICL), offering a practical solution for data augmentation in data scarce scenarios. While prior work has shown the potential of LLMs to improve downstream task performance through augmenting underrepresented groups, these benefits often assume access to a subset of unbiased in-context examples, representative of the real dataset. In real-world settings, however, data is frequently noisy and demographically skewed. In this paper, we systematically study how statistical biases within in-context examples propagate to the distribution of synthetic tabular data, showing that even mild in-context biases lead to global statistical distortions. We further introduce an adversarial scenario where a malicious contributor can inject bias into the synthetic dataset via a subset of in-context examples, ultimately compromising the fairness of downstream classifiers for a targeted and protected subgroup. Finally, we evaluate mitigation strategies based on preprocessing in-context examples, demonstrating that while such interventions can attenuate disparity, the inherent sensitivity of LLMs to adversarial prompts remains a persistent challenge. Our findings highlight a critical new vulnerability in LLM-based data generation pipelines within sensitive domains.
title In-Context Bias Propagation in LLM-Based Tabular Data Generation
topic Machine Learning
url https://arxiv.org/abs/2506.09630