Less Is More? Examining Fairness in Pruned Large Language Models for Summarising Opinions

Fuente: arXiv
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Main Authors: Huang, Nannan, Fayek, Haytham M., Zhang, Xiuzhen
Format: Preprint
Published: 2025
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author Huang, Nannan
Fayek, Haytham M.
Zhang, Xiuzhen
author_facet Huang, Nannan
Fayek, Haytham M.
Zhang, Xiuzhen
contents Model compression through post-training pruning offers a way to reduce model size and computational requirements without significantly impacting model performance. However, the effect of pruning on the fairness of LLM-generated summaries remains unexplored, particularly for opinion summarisation where biased outputs could influence public views.In this paper, we present a comprehensive empirical analysis of opinion summarisation, examining three state-of-the-art pruning methods and various calibration sets across three open-source LLMs using four fairness metrics. Our systematic analysis reveals that pruning methods have a greater impact on fairness than calibration sets. Building on these insights, we propose High Gradient Low Activation (HGLA) pruning, which identifies and removes parameters that are redundant for input processing but influential in output generation. Our experiments demonstrate that HGLA can better maintain or even improve fairness compared to existing methods, showing promise across models and tasks where traditional methods have limitations. Our human evaluation shows HGLA-generated outputs are fairer than existing state-of-the-art pruning methods. Code is available at: https://github.com/amberhuang01/HGLA.
format Preprint
id arxiv_https___arxiv_org_abs_2508_17610
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Less Is More? Examining Fairness in Pruned Large Language Models for Summarising Opinions
Huang, Nannan
Fayek, Haytham M.
Zhang, Xiuzhen
Computation and Language
Model compression through post-training pruning offers a way to reduce model size and computational requirements without significantly impacting model performance. However, the effect of pruning on the fairness of LLM-generated summaries remains unexplored, particularly for opinion summarisation where biased outputs could influence public views.In this paper, we present a comprehensive empirical analysis of opinion summarisation, examining three state-of-the-art pruning methods and various calibration sets across three open-source LLMs using four fairness metrics. Our systematic analysis reveals that pruning methods have a greater impact on fairness than calibration sets. Building on these insights, we propose High Gradient Low Activation (HGLA) pruning, which identifies and removes parameters that are redundant for input processing but influential in output generation. Our experiments demonstrate that HGLA can better maintain or even improve fairness compared to existing methods, showing promise across models and tasks where traditional methods have limitations. Our human evaluation shows HGLA-generated outputs are fairer than existing state-of-the-art pruning methods. Code is available at: https://github.com/amberhuang01/HGLA.
title Less Is More? Examining Fairness in Pruned Large Language Models for Summarising Opinions
topic Computation and Language
url https://arxiv.org/abs/2508.17610