Stockholm university
Department of Statistics

Seminar: Stina Zetterström, University of Cambridge, UK

Seminar

Date: Wednesday 8 October 2025

Time: 13.00 – 14.00

Location: Campus Albano, Lecture room 2, house 1, level 2

Alternative Formulations of the Allocation Probability Test Statistic to Enhance Power in Response-Adaptive Clinical Trials

Abstract

In response-adaptive clinical trials, treatment allocation probabilities are updated throughout the study based on the outcome of previous participants in the study. One reason for this strategy is to increase the probability that participants receive the most effective treatment compared to equal randomisation. However, imbalances in allocation can reduce statistical power when testing for treatment differences. Recent research has introduced a testing approach based on allocation probabilities (AP) rather than direct outcomes, which can improve power. I will present alternative AP test formulations to further increase power in response-adaptive settings. Using simulation studies with the Bayesian Response Adaptive Randomization (BRAR) algorithm for binary outcomes in a two-arm trial, the performance of the investigated functional forms is assessed. The results indicate that changing the functional form of the AP test statistic can substantially increase the power compared to the original formulation. Furthermore, the AP test can offer greater power than traditional methods while maintaining type I error control. Although the evaluation focuses on BRAR, the AP framework is applicable to any response-adaptive randomisation, and its performance can be investigated in those contexts.

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Last updated: September 16, 2025

Source: Department of Statistics

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