Like Oil and Water: Group Robustness Methods and Poisoning Defenses May Be at Odds

Fuente: arXiv
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Autori principali: Panaitescu-Liess, Michael-Andrei, Kaya, Yigitcan, Zhu, Sicheng, Huang, Furong, Dumitras, Tudor
Natura: Preprint
Pubblicazione: 2025
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author Panaitescu-Liess, Michael-Andrei
Kaya, Yigitcan
Zhu, Sicheng
Huang, Furong
Dumitras, Tudor
author_facet Panaitescu-Liess, Michael-Andrei
Kaya, Yigitcan
Zhu, Sicheng
Huang, Furong
Dumitras, Tudor
contents Group robustness has become a major concern in machine learning (ML) as conventional training paradigms were found to produce high error on minority groups. Without explicit group annotations, proposed solutions rely on heuristics that aim to identify and then amplify the minority samples during training. In our work, we first uncover a critical shortcoming of these methods: an inability to distinguish legitimate minority samples from poison samples in the training set. By amplifying poison samples as well, group robustness methods inadvertently boost the success rate of an adversary -- e.g., from $0\%$ without amplification to over $97\%$ with it. Notably, we supplement our empirical evidence with an impossibility result proving this inability of a standard heuristic under some assumptions. Moreover, scrutinizing recent poisoning defenses both in centralized and federated learning, we observe that they rely on similar heuristics to identify which samples should be eliminated as poisons. In consequence, minority samples are eliminated along with poisons, which damages group robustness -- e.g., from $55\%$ without the removal of the minority samples to $41\%$ with it. Finally, as they pursue opposing goals using similar heuristics, our attempt to alleviate the trade-off by combining group robustness methods and poisoning defenses falls short. By exposing this tension, we also hope to highlight how benchmark-driven ML scholarship can obscure the trade-offs among different metrics with potentially detrimental consequences.
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id arxiv_https___arxiv_org_abs_2504_02142
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Like Oil and Water: Group Robustness Methods and Poisoning Defenses May Be at Odds
Panaitescu-Liess, Michael-Andrei
Kaya, Yigitcan
Zhu, Sicheng
Huang, Furong
Dumitras, Tudor
Machine Learning
Cryptography and Security
Group robustness has become a major concern in machine learning (ML) as conventional training paradigms were found to produce high error on minority groups. Without explicit group annotations, proposed solutions rely on heuristics that aim to identify and then amplify the minority samples during training. In our work, we first uncover a critical shortcoming of these methods: an inability to distinguish legitimate minority samples from poison samples in the training set. By amplifying poison samples as well, group robustness methods inadvertently boost the success rate of an adversary -- e.g., from $0\%$ without amplification to over $97\%$ with it. Notably, we supplement our empirical evidence with an impossibility result proving this inability of a standard heuristic under some assumptions. Moreover, scrutinizing recent poisoning defenses both in centralized and federated learning, we observe that they rely on similar heuristics to identify which samples should be eliminated as poisons. In consequence, minority samples are eliminated along with poisons, which damages group robustness -- e.g., from $55\%$ without the removal of the minority samples to $41\%$ with it. Finally, as they pursue opposing goals using similar heuristics, our attempt to alleviate the trade-off by combining group robustness methods and poisoning defenses falls short. By exposing this tension, we also hope to highlight how benchmark-driven ML scholarship can obscure the trade-offs among different metrics with potentially detrimental consequences.
title Like Oil and Water: Group Robustness Methods and Poisoning Defenses May Be at Odds
topic Machine Learning
Cryptography and Security
url https://arxiv.org/abs/2504.02142