Truthfulness of Calibration Measures

Fuente: arXiv
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Main Authors: Haghtalab, Nika, Qiao, Mingda, Yang, Kunhe, Zhao, Eric
Format: Preprint
Published: 2024
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author Haghtalab, Nika
Qiao, Mingda
Yang, Kunhe
Zhao, Eric
author_facet Haghtalab, Nika
Qiao, Mingda
Yang, Kunhe
Zhao, Eric
contents We initiate the study of the truthfulness of calibration measures in sequential prediction. A calibration measure is said to be truthful if the forecaster (approximately) minimizes the expected penalty by predicting the conditional expectation of the next outcome, given the prior distribution of outcomes. Truthfulness is an important property of calibration measures, ensuring that the forecaster is not incentivized to exploit the system with deliberate poor forecasts. This makes it an essential desideratum for calibration measures, alongside typical requirements, such as soundness and completeness. We conduct a taxonomy of existing calibration measures and their truthfulness. Perhaps surprisingly, we find that all of them are far from being truthful. That is, under existing calibration measures, there are simple distributions on which a polylogarithmic (or even zero) penalty is achievable, while truthful prediction leads to a polynomial penalty. Our main contribution is the introduction of a new calibration measure termed the Subsampled Smooth Calibration Error (SSCE) under which truthful prediction is optimal up to a constant multiplicative factor.
format Preprint
id arxiv_https___arxiv_org_abs_2407_13979
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Truthfulness of Calibration Measures
Haghtalab, Nika
Qiao, Mingda
Yang, Kunhe
Zhao, Eric
Machine Learning
Data Structures and Algorithms
We initiate the study of the truthfulness of calibration measures in sequential prediction. A calibration measure is said to be truthful if the forecaster (approximately) minimizes the expected penalty by predicting the conditional expectation of the next outcome, given the prior distribution of outcomes. Truthfulness is an important property of calibration measures, ensuring that the forecaster is not incentivized to exploit the system with deliberate poor forecasts. This makes it an essential desideratum for calibration measures, alongside typical requirements, such as soundness and completeness. We conduct a taxonomy of existing calibration measures and their truthfulness. Perhaps surprisingly, we find that all of them are far from being truthful. That is, under existing calibration measures, there are simple distributions on which a polylogarithmic (or even zero) penalty is achievable, while truthful prediction leads to a polynomial penalty. Our main contribution is the introduction of a new calibration measure termed the Subsampled Smooth Calibration Error (SSCE) under which truthful prediction is optimal up to a constant multiplicative factor.
title Truthfulness of Calibration Measures
topic Machine Learning
Data Structures and Algorithms
url https://arxiv.org/abs/2407.13979