A computational method for type I error rate control in power-maximizing response-adaptive randomization

Fuente: arXiv
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Main Authors: Baas, Stef, Pin, Lukas, Villar, Sofía S., Rosenberger, William F.
Format: Preprint
Published: 2025
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author Baas, Stef
Pin, Lukas
Villar, Sofía S.
Rosenberger, William F.
author_facet Baas, Stef
Pin, Lukas
Villar, Sofía S.
Rosenberger, William F.
contents Maximizing statistical power in experimental design often involves imbalanced treatment allocation, but several challenges hinder its practical adoption: (1) the misconception that equal allocation always maximizes power, (2) when only targeting maximum power, more than half the participants may be expected to obtain inferior treatment, and (3) response-adaptive randomization (RAR) targeting maximum statistical power may inflate type I error rates substantially. Recent work identified issue (3) and proposed a novel allocation procedure combined with the asymptotic score test. Instead, the current research focuses on finite-sample guarantees. First, we analyze the power for traditional power-maximizing RAR procedures under exact tests, including a novel generalization of Boschloo's test. Second, we evaluate constrained Markov decision process (CMDP) RAR procedures under exact tests. These procedures target maximum average power under constraints on pointwise and average type I error rates, with averages taken across the parametric space. A combination of the unconditional exact test and the CMDP procedure protecting allocations to the superior arm gives the best performance, providing substantial power gains over equal allocation while allocating more participants in expectation to the superior treatment. Future research could focus on the randomization test, in which CMDP procedures exhibited lower power compared to other examined RAR procedures.
format Preprint
id arxiv_https___arxiv_org_abs_2509_12448
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A computational method for type I error rate control in power-maximizing response-adaptive randomization
Baas, Stef
Pin, Lukas
Villar, Sofía S.
Rosenberger, William F.
Methodology
Maximizing statistical power in experimental design often involves imbalanced treatment allocation, but several challenges hinder its practical adoption: (1) the misconception that equal allocation always maximizes power, (2) when only targeting maximum power, more than half the participants may be expected to obtain inferior treatment, and (3) response-adaptive randomization (RAR) targeting maximum statistical power may inflate type I error rates substantially. Recent work identified issue (3) and proposed a novel allocation procedure combined with the asymptotic score test. Instead, the current research focuses on finite-sample guarantees. First, we analyze the power for traditional power-maximizing RAR procedures under exact tests, including a novel generalization of Boschloo's test. Second, we evaluate constrained Markov decision process (CMDP) RAR procedures under exact tests. These procedures target maximum average power under constraints on pointwise and average type I error rates, with averages taken across the parametric space. A combination of the unconditional exact test and the CMDP procedure protecting allocations to the superior arm gives the best performance, providing substantial power gains over equal allocation while allocating more participants in expectation to the superior treatment. Future research could focus on the randomization test, in which CMDP procedures exhibited lower power compared to other examined RAR procedures.
title A computational method for type I error rate control in power-maximizing response-adaptive randomization
topic Methodology
url https://arxiv.org/abs/2509.12448