Sample size calculation in hierarchical 2×2 factorial trials with unequal cluster sizes.

ABSTRACT: Motivated by a suicide prevention trial with hierarchical treatment allocation (cluster-level and individual-level treatments), we address the sample size requirements for testing the treatment effects as well as their interaction. We assume a linear mixed model, within which two types of treatment effect estimands (controlled effect and marginal effect) are defined. For each null hypothesis corresponding to an estimand, we derive sample size formulas based on large-sample z-approximation, and provide finite-sample modifications based on a t-approximation. We relax the equal cluster size assumption and express the sample size formulas as functions of the mean and coefficient of variation of cluster sizes. We show that the sample size requirement for testing the controlled effect of the clu

SUBMITTER: Tian Z 

PROVIDER: S-EPMC8962918 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature