Power calculation for cross-sectional stepped wedge cluster randomized trials with variable cluster sizes.

ABSTRACT: Standard sample size calculation formulas for stepped wedge cluster randomized trials (SW-CRTs) assume that cluster sizes are equal. When cluster sizes vary substantially, ignoring this variation may lead to an under-powered study. We investigate the relative efficiency of a SW-CRT with varying cluster sizes to equal cluster sizes, and derive variance estimators for the intervention effect that account for this variation under a mixed effects model-a commonly used approach for analyzing data from cluster randomized trials. When cluster sizes vary, the power of a SW-CRT depends on the order in which clusters receive the intervention, which is determined through randomization. We first derive a variance formula that corresponds to any particular realization of the randomized sequence and pro

SUBMITTER: Harrison LJ 

PROVIDER: S-EPMC7165039 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature