Sample size calculations for stepped wedge and cluster randomised trials: a unified approach.

ABSTRACT:

Objectives

To clarify and illustrate sample size calculations for the cross-sectional stepped wedge cluster randomized trial (SW-CRT) and to present a simple approach for comparing the efficiencies of competing designs within a unified framework.

Study design and setting

We summarize design effects for the SW-CRT, the parallel cluster randomized trial (CRT), and the parallel cluster randomized trial with before and after observations (CRT-BA), assuming cross-sectional samples are selected over time. We present new formulas that enable trialists to determine the required cluster size for a given number of clusters. We illustrate by example how to implement the presented design effects and give practical guidance on the design of stepped wedge studies.

Results

For a fix

SUBMITTER: Hemming K 

PROVIDER: S-EPMC4687983 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature