Does Quantization Change What Agreement Means? A Paired Audit of Homogeneous LLM Panels

Ananto Nayan Bala


Abstract
Agreement among repeated large language model (LLM) responses is often used as a confidence signal. We test whether that signal changes after quantization by comparing five-response panels from the same checkpoints at FP16 and 4-bit NF4. We evaluate two open models on 300 TruthfulQA multiple-choice questions and 300 GSM8K problems, matching prompts, sampling settings, and seeds. Under strict parsing, quantization reduces GSM8K panel accuracy by 10.5 percentage points for Qwen2.5-3B and 6.3 for Phi-3.5-mini. The probability that all five responses are wrong rises by 9.0 and 5.0 points. Agreement also becomes less useful for selecting reliable answers, but all-wrong panels do not consistently become more likely to give one identical answer. Relaxed parsing preserves the selective-reliability result for both models, although Phi’s panel-accuracy and all-wrong differences become inconclusive. On TruthfulQA, Phi degrades while Qwen is largely stable. Quantization can therefore reduce panel reliability without consistently pushing all members toward the same wrong answer.
Anthology ID:
2026.uncertainlp-main.37
Volume:
The Proceedings of the Third Workshop on Uncertainty-Aware NLP
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Wilker Aziz, Jonathan Berant, Bryan Eikema, Evgenia Ilia, Marie-Catherine de Marneffe, Barbara Plank, Artem Shelmanov, Swabha Swayamdipta, Jörg Tiedemann, Artem Vazhentsev, Raúl Vázquez, Chrysoula Zerva
Venues:
UncertaiNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
618–624
Language:
URL:
https://aclanthology.org/2026.uncertainlp-main.37/
DOI:
Bibkey:
Cite (ACL):
Ananto Nayan Bala. 2026. Does Quantization Change What Agreement Means? A Paired Audit of Homogeneous LLM Panels. In The Proceedings of the Third Workshop on Uncertainty-Aware NLP, pages 618–624, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Does Quantization Change What Agreement Means? A Paired Audit of Homogeneous LLM Panels (Nayan Bala, UncertaiNLP 2026)
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PDF:
https://aclanthology.org/2026.uncertainlp-main.37.pdf