Pandora's Regret: A Proper Scoring Rule for Evaluating Sequential Search

Fuente: arXiv
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Autori principali: Flores, Gerardo A., Deshpande, Yash, Brea, Jannis R., Wilson, Ashia C.
Natura: Preprint
Pubblicazione: 2026
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author Flores, Gerardo A.
Deshpande, Yash
Brea, Jannis R.
Wilson, Ashia C.
author_facet Flores, Gerardo A.
Deshpande, Yash
Brea, Jannis R.
Wilson, Ashia C.
contents In sequential search, alternatives are tested until the true class is found. Standard proper scoring rules like log loss are local, ignoring the ranking of competitors and misaligning model evaluation with search utility. We show that sequential search induces a pairwise structure that overcomes this. By analyzing the expected cost of optimal search under varying testing costs, we derive Pandora's Regret: a closed-form, pairwise-additive, and strictly proper scoring rule. Pandora's Regret both elicits true probabilities and penalizes rank-reversing miscalibrations where distractors outrank the true class. Our construction yields a one-parameter Beta family that balances penalties for rank-swapping versus probability magnitude, while retaining a grounded interpretation as expected search cost. We prove that log loss, accuracy, and macro-F1 rely on implicit decision models misaligned with sequential search. Across 597 MedMNIST models, Pandora-based metrics better predict clinical diagnostic costs than standard alternatives, extending decision-theoretic scoring rule construction to the multiclass setting.
format Preprint
id arxiv_https___arxiv_org_abs_2605_01936
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pandora's Regret: A Proper Scoring Rule for Evaluating Sequential Search
Flores, Gerardo A.
Deshpande, Yash
Brea, Jannis R.
Wilson, Ashia C.
Machine Learning
In sequential search, alternatives are tested until the true class is found. Standard proper scoring rules like log loss are local, ignoring the ranking of competitors and misaligning model evaluation with search utility. We show that sequential search induces a pairwise structure that overcomes this. By analyzing the expected cost of optimal search under varying testing costs, we derive Pandora's Regret: a closed-form, pairwise-additive, and strictly proper scoring rule. Pandora's Regret both elicits true probabilities and penalizes rank-reversing miscalibrations where distractors outrank the true class. Our construction yields a one-parameter Beta family that balances penalties for rank-swapping versus probability magnitude, while retaining a grounded interpretation as expected search cost. We prove that log loss, accuracy, and macro-F1 rely on implicit decision models misaligned with sequential search. Across 597 MedMNIST models, Pandora-based metrics better predict clinical diagnostic costs than standard alternatives, extending decision-theoretic scoring rule construction to the multiclass setting.
title Pandora's Regret: A Proper Scoring Rule for Evaluating Sequential Search
topic Machine Learning
url https://arxiv.org/abs/2605.01936