Parametric Scaling Law of Tuning Bias in Conformal Prediction

Fuente: arXiv
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Autori principali: Zeng, Hao, Liu, Kangdao, Jing, Bingyi, Wei, Hongxin
Natura: Preprint
Pubblicazione: 2025
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author Zeng, Hao
Liu, Kangdao
Jing, Bingyi
Wei, Hongxin
author_facet Zeng, Hao
Liu, Kangdao
Jing, Bingyi
Wei, Hongxin
contents Conformal prediction is a popular framework of uncertainty quantification that constructs prediction sets with coverage guarantees. To uphold the exchangeability assumption, many conformal prediction methods necessitate an additional holdout set for parameter tuning. Yet, the impact of violating this principle on coverage remains underexplored, making it ambiguous in practical applications. In this work, we empirically find that the tuning bias - the coverage gap introduced by leveraging the same dataset for tuning and calibration, is negligible for simple parameter tuning in many conformal prediction methods. In particular, we observe the scaling law of the tuning bias: this bias increases with parameter space complexity and decreases with calibration set size. Formally, we establish a theoretical framework to quantify the tuning bias and provide rigorous proof for the scaling law of the tuning bias by deriving its upper bound. In the end, we discuss how to reduce the tuning bias, guided by the theories we developed.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03023
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Parametric Scaling Law of Tuning Bias in Conformal Prediction
Zeng, Hao
Liu, Kangdao
Jing, Bingyi
Wei, Hongxin
Machine Learning
Statistics Theory
Methodology
Conformal prediction is a popular framework of uncertainty quantification that constructs prediction sets with coverage guarantees. To uphold the exchangeability assumption, many conformal prediction methods necessitate an additional holdout set for parameter tuning. Yet, the impact of violating this principle on coverage remains underexplored, making it ambiguous in practical applications. In this work, we empirically find that the tuning bias - the coverage gap introduced by leveraging the same dataset for tuning and calibration, is negligible for simple parameter tuning in many conformal prediction methods. In particular, we observe the scaling law of the tuning bias: this bias increases with parameter space complexity and decreases with calibration set size. Formally, we establish a theoretical framework to quantify the tuning bias and provide rigorous proof for the scaling law of the tuning bias by deriving its upper bound. In the end, we discuss how to reduce the tuning bias, guided by the theories we developed.
title Parametric Scaling Law of Tuning Bias in Conformal Prediction
topic Machine Learning
Statistics Theory
Methodology
url https://arxiv.org/abs/2502.03023