Cluster randomised trials with different numbers of measurements at baseline and endline: Sample size and optimal allocation.

ABSTRACT:

Background/aims

Published methods for sample size calculation for cluster randomised trials with baseline data are inflexible and primarily assume an equal amount of data collected at baseline and endline, that is, before and after the intervention has been implemented in some clusters. We extend these methods to any amount of baseline and endline data. We explain how to explore sample size for a trial if some baseline data from the trial clusters have already been collected as part of a separate study. Where such data aren't available, we show how to choose the proportion of data collection devoted to the baseline within the trial, when a particular cluster size or range of cluster sizes is proposed.

Methods

We provide a design effect given the cluster size and correlation

SUBMITTER: Copas AJ 

PROVIDER: S-EPMC7334046 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature