DCRM: A Heuristic to Measure Response Pair Quality in Preference Optimization

Fuente: arXiv
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Autores principales: Huang, Chengyu, Goyal, Tanya
Formato: Preprint
Publicado: 2025
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author Huang, Chengyu
Goyal, Tanya
author_facet Huang, Chengyu
Goyal, Tanya
contents Recent research has attempted to associate preference optimization (PO) performance with the underlying preference datasets. In this work, our observation is that the differences between the preferred response $y^+$ and dispreferred response $y^-$ influence what LLMs can learn, which may not match the desirable differences to learn. Therefore, we use distance and reward margin to quantify these differences, and combine them to get Distance Calibrated Reward Margin (DCRM), a metric that measures the quality of a response pair for PO. Intuitively, DCRM encourages minimal noisy differences and maximal desired differences. With this, we study 3 types of commonly used preference datasets, classified along two axes: the source of the responses and the preference labeling function. We establish a general correlation between higher DCRM of the training set and better learning outcome. Inspired by this, we propose a best-of-$N^2$ pairing method that selects response pairs with the highest DCRM. Empirically, in various settings, our method produces training datasets that can further improve models' performance on AlpacaEval, MT-Bench, and Arena-Hard over the existing training sets.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14157
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle DCRM: A Heuristic to Measure Response Pair Quality in Preference Optimization
Huang, Chengyu
Goyal, Tanya
Computation and Language
Artificial Intelligence
Machine Learning
Recent research has attempted to associate preference optimization (PO) performance with the underlying preference datasets. In this work, our observation is that the differences between the preferred response $y^+$ and dispreferred response $y^-$ influence what LLMs can learn, which may not match the desirable differences to learn. Therefore, we use distance and reward margin to quantify these differences, and combine them to get Distance Calibrated Reward Margin (DCRM), a metric that measures the quality of a response pair for PO. Intuitively, DCRM encourages minimal noisy differences and maximal desired differences. With this, we study 3 types of commonly used preference datasets, classified along two axes: the source of the responses and the preference labeling function. We establish a general correlation between higher DCRM of the training set and better learning outcome. Inspired by this, we propose a best-of-$N^2$ pairing method that selects response pairs with the highest DCRM. Empirically, in various settings, our method produces training datasets that can further improve models' performance on AlpacaEval, MT-Bench, and Arena-Hard over the existing training sets.
title DCRM: A Heuristic to Measure Response Pair Quality in Preference Optimization
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2506.14157