Adaptive Experimental Design for Policy Learning

Fuente: arXiv
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Hauptverfasser: Kato, Masahiro, Okumura, Kyohei, Ishihara, Takuya, Kitagawa, Toru
Format: Preprint
Veröffentlicht: 2024
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author Kato, Masahiro
Okumura, Kyohei
Ishihara, Takuya
Kitagawa, Toru
author_facet Kato, Masahiro
Okumura, Kyohei
Ishihara, Takuya
Kitagawa, Toru
contents This study investigates the contextual best arm identification (BAI) problem, aiming to design an adaptive experiment to identify the best treatment arm conditioned on contextual information (covariates). We consider a decision-maker who assigns treatment arms to experimental units during an experiment and recommends the estimated best treatment arm based on the contexts at the end of the experiment. The decision-maker uses a policy for recommendations, which is a function that provides the estimated best treatment arm given the contexts. In our evaluation, we focus on the worst-case expected regret, a relative measure between the expected outcomes of an optimal policy and our proposed policy. We derive a lower bound for the expected simple regret and then propose a strategy called Adaptive Sampling-Policy Learning (PLAS). We prove that this strategy is minimax rate-optimal in the sense that its leading factor in the regret upper bound matches the lower bound as the number of experimental units increases.
format Preprint
id arxiv_https___arxiv_org_abs_2401_03756
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Adaptive Experimental Design for Policy Learning
Kato, Masahiro
Okumura, Kyohei
Ishihara, Takuya
Kitagawa, Toru
Machine Learning
Artificial Intelligence
Econometrics
Methodology
This study investigates the contextual best arm identification (BAI) problem, aiming to design an adaptive experiment to identify the best treatment arm conditioned on contextual information (covariates). We consider a decision-maker who assigns treatment arms to experimental units during an experiment and recommends the estimated best treatment arm based on the contexts at the end of the experiment. The decision-maker uses a policy for recommendations, which is a function that provides the estimated best treatment arm given the contexts. In our evaluation, we focus on the worst-case expected regret, a relative measure between the expected outcomes of an optimal policy and our proposed policy. We derive a lower bound for the expected simple regret and then propose a strategy called Adaptive Sampling-Policy Learning (PLAS). We prove that this strategy is minimax rate-optimal in the sense that its leading factor in the regret upper bound matches the lower bound as the number of experimental units increases.
title Adaptive Experimental Design for Policy Learning
topic Machine Learning
Artificial Intelligence
Econometrics
Methodology
url https://arxiv.org/abs/2401.03756