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Bayesian adaptive designs enable flexible clinical trials by adapting features based on accumulating data. Among these, Bayesian Response-Adaptive Randomization (BRAR) skews patient allocation towards more promising treatments based on…

Methodology · Statistics 2025-12-05 Daniel Kaddaj , Stef Baas , Edwin Y. N. Tang , David S. Robertson , Lukas Pin , Sofía S. Villar

This paper addresses the challenge of improving finite sample performance in Ranking and Selection by developing a Bahadur-Rao type expansion for the Probability of Correct Selection (PCS). While traditional large deviations approximations…

Machine Learning · Statistics 2024-11-19 Xinbo Shi , Yijie Peng , Bruno Tuffin

To ensure reliable causal conclusions from observational (i.e., non-randomized) studies, researchers routinely conduct sensitivity analysis to assess robustness to hidden bias due to unmeasured confounding. In matched observational studies…

Methodology · Statistics 2025-11-11 Siyu Heng , Elaine K. Chiu , Hyunseung Kang

Scientific experimentation is largely driven by statistical hypothesis testing to determine significant differences in interventions. Traditionally, experimenters allocate samples uniformly between each intervention. However, such an…

Response-adaptive clinical trial designs allow targeting a given objective by skewing the allocation of participants to treatments based on observed outcomes. Response-adaptive designs face greater regulatory scrutiny due to potential type…

Methodology · Statistics 2025-03-19 Stef Baas , Peter Jacko , Sofía S. Villar

The Bayesian Optimal Phase II (BOP2) framework is a flexible trial design that can naturally facilitate complex adaptations due to its Bayesian setting. BOP2 uses equal randomisation and equally placed interim analyses in its design, but it…

Applications · Statistics 2025-11-19 Connor Fitchett , Ayon Mukherjee , Sofía S. Villar , David S. Robertson

Adapting the final sample size of a trial to the evidence accruing during the trial is a natural way to address planning uncertainty. Designs with adaptive sample size need to account for their optional stopping to guarantee strict type-I…

In adaptive clinical trials, the conventional end-of-trial point estimate of a treatment effect is prone to bias, that is, a systematic tendency to deviate from its true value. As stated in recent FDA guidance on adaptive designs, it is…

Judging scholarly posters creates a challenge to assign the judges efficiently. If there are many posters and few reviews per judge, the commonly used Balanced Incomplete Block Design is not a feasible option. An additional challenge is an…

Applications · Statistics 2018-06-04 Xiaoyue Niu , James L. Rosenberger

The majority of response-adaptive randomisation (RAR) designs in the literature rely on efficacy data to guide dynamic patient allocation. However, their applicability becomes limited in settings where efficacy outcomes, such as survival,…

Methodology · Statistics 2026-02-23 Maria Vittoria Chiaruttini , Lukas Pin , Sofia S. Villar

We consider the optimal experimental design problem of allocating subjects to treatment or control when subjects participate in multiple, separate controlled experiments within a short time-frame and subject covariate information is…

Methodology · Statistics 2024-12-16 William Fisher , Qiong Zhang , Lulu Kang , Xinwei Deng

Adaptive sample size re-estimation, early stopping, and trial re-design at interim analyses can reduce expected sample sizes in randomised trials. Cluster randomised trials, in which groups of participants are randomly allocated to…

Methodology · Statistics 2026-03-09 Samuel I. Watson , James Martin

Optimal two-treatment, $p$ period crossover designs for binary responses are determined. The optimal designs are obtained by minimizing the variance of the treatment contrast estimator over all possible allocations of $n$ subjects to $2^p$…

Methodology · Statistics 2015-05-12 S. Mukhopadhyay , S. P. Singh , A. Dey

We study how to efficiently estimate average treatment effects (ATEs) using adaptive experiments. In adaptive experiments, experimenters sequentially assign treatments to experimental units while updating treatment assignment probabilities…

Machine Learning · Statistics 2025-02-21 Masahiro Kato , Takuya Ishihara , Junya Honda , Yusuke Narita

Bayesian response adaptive clinical trials are currently evaluating experimental therapies for several diseases. Adaptive decisions, such as pre-planned variations of the randomization probabilities, attempt to accelerate the development of…

Methodology · Statistics 2021-05-25 Marta Bonsaglio , Sandra Fortini , Steffen Ventz , Lorenzo Trippa

An adaptive design adjusts dynamically as information is accrued and a consequence of applying an adaptive design is the potential for inducing small-sample bias in estimates. In psychometrics and psychophysics, a common class of studies…

Methodology · Statistics 2025-02-17 Simon Bang Kristensen , Katrine Bødkergaard , Bo Martin Bibby

In clinical trials, there is potential to improve precision and reduce the required sample size by appropriately adjusting for baseline variables in the statistical analysis. This is called covariate adjustment. Despite recommendations by…

Methodology · Statistics 2022-06-20 Kelly Van Lancker , Joshua Betz , Michael Rosenblum

In nonstandard testing environments, researchers often derive ad hoc tests with correct (asymptotic) size, but their optimality properties are typically unknown a priori and difficult to assess. This paper develops a numerical framework for…

Econometrics · Economics 2025-12-24 Philipp Ketz , Adam McCloskey , Jan Scherer

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…

Machine Learning · Computer Science 2025-06-23 Masahiro Kato , Kyohei Okumura , Takuya Ishihara , Toru Kitagawa

The treatment allocation mechanism in a randomized clinical trial can be optimized by maximizing the nonparametric efficiency bound for a specific measure of treatment effect. Optimal treatment allocations which may or may not depend on…

Methodology · Statistics 2025-05-23 Wei Zhang , Zhiwei Zhang , Aiyi Liu