COIN: Uncertainty-Guarding Selective Question Answering for Foundation Models with Provable Risk Guarantees

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Hauptverfasser: Wang, Zhiyuan, Duan, Jinhao, Wang, Qingni, Zhu, Xiaofeng, Chen, Tianlong, Shi, Xiaoshuang, Xu, Kaidi
Format: Preprint
Veröffentlicht: 2025
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author Wang, Zhiyuan
Duan, Jinhao
Wang, Qingni
Zhu, Xiaofeng
Chen, Tianlong
Shi, Xiaoshuang
Xu, Kaidi
author_facet Wang, Zhiyuan
Duan, Jinhao
Wang, Qingni
Zhu, Xiaofeng
Chen, Tianlong
Shi, Xiaoshuang
Xu, Kaidi
contents Uncertainty quantification (UQ) for foundation models is essential to identify and mitigate potential hallucinations in automatically generated text. However, heuristic UQ approaches lack formal guarantees for key metrics such as the false discovery rate (FDR) in selective prediction. Previous work adopts the split conformal prediction (SCP) framework to ensure desired coverage of admissible answers by constructing prediction sets, but these sets often contain incorrect candidates, limiting their practical utility. To address this, we propose COIN, an uncertainty-guarding selection framework that calibrates statistically valid thresholds to filter a single generated answer per question under user-specified FDR constraints. COIN estimates the empirical error rate on a calibration set and applies confidence interval methods such as Clopper-Pearson to establish a high-probability upper bound on the true error rate (i.e., FDR). This enables the selection of the largest uncertainty threshold that ensures FDR control on test data while significantly increasing sample retention. We demonstrate COIN's robustness in risk control, strong test-time power in retaining admissible answers, and predictive efficiency under limited calibration data across both general and multimodal text generation tasks. Furthermore, we show that employing alternative upper bound constructions and UQ strategies can further boost COIN's power performance, which underscores its extensibility and adaptability to diverse application scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2506_20178
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle COIN: Uncertainty-Guarding Selective Question Answering for Foundation Models with Provable Risk Guarantees
Wang, Zhiyuan
Duan, Jinhao
Wang, Qingni
Zhu, Xiaofeng
Chen, Tianlong
Shi, Xiaoshuang
Xu, Kaidi
Computation and Language
Artificial Intelligence
Machine Learning
Uncertainty quantification (UQ) for foundation models is essential to identify and mitigate potential hallucinations in automatically generated text. However, heuristic UQ approaches lack formal guarantees for key metrics such as the false discovery rate (FDR) in selective prediction. Previous work adopts the split conformal prediction (SCP) framework to ensure desired coverage of admissible answers by constructing prediction sets, but these sets often contain incorrect candidates, limiting their practical utility. To address this, we propose COIN, an uncertainty-guarding selection framework that calibrates statistically valid thresholds to filter a single generated answer per question under user-specified FDR constraints. COIN estimates the empirical error rate on a calibration set and applies confidence interval methods such as Clopper-Pearson to establish a high-probability upper bound on the true error rate (i.e., FDR). This enables the selection of the largest uncertainty threshold that ensures FDR control on test data while significantly increasing sample retention. We demonstrate COIN's robustness in risk control, strong test-time power in retaining admissible answers, and predictive efficiency under limited calibration data across both general and multimodal text generation tasks. Furthermore, we show that employing alternative upper bound constructions and UQ strategies can further boost COIN's power performance, which underscores its extensibility and adaptability to diverse application scenarios.
title COIN: Uncertainty-Guarding Selective Question Answering for Foundation Models with Provable Risk Guarantees
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2506.20178