When Quantization Affects Confidence of Large Language Models?

Irina Proskurina, Luc Brun, Guillaume Metzler, Julien Velcin


Abstract
Recent studies introduced effective compression techniques for Large Language Models (LLMs) via post-training quantization or low-bit weight representation. Although quantized weights offer storage efficiency and allow for faster inference, existing works have indicated that quantization might compromise performance and exacerbate biases in LLMs.This study investigates the confidence and calibration of quantized models, considering factors such as language model type and scale as contributors to quantization loss.Firstly, we reveal that quantization with GPTQ to 4-bit results in a decrease in confidence regarding true labels, with varying impacts observed among different language models. Secondly, we observe fluctuations in the impact on confidence across different scales. Finally, we propose an explanation for quantization loss based on confidence levels, indicating that quantization disproportionately affects samples where the full model exhibited low confidence levels in the first place.We make our code and quantized models publicly available.
Anthology ID:
2024.findings-naacl.124
Volume:
Findings of the Association for Computational Linguistics: NAACL 2024
Month:
June
Year:
2024
Address:
Mexico City, Mexico
Editors:
Kevin Duh, Helena Gomez, Steven Bethard
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1918–1928
Language:
URL:
https://aclanthology.org/2024.findings-naacl.124
DOI:
Bibkey:
Cite (ACL):
Irina Proskurina, Luc Brun, Guillaume Metzler, and Julien Velcin. 2024. When Quantization Affects Confidence of Large Language Models?. In Findings of the Association for Computational Linguistics: NAACL 2024, pages 1918–1928, Mexico City, Mexico. Association for Computational Linguistics.
Cite (Informal):
When Quantization Affects Confidence of Large Language Models? (Proskurina et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-naacl.124.pdf