Cluster-Randomized Studies

Empirical Power and Sample Size Calculations for Cluster-Randomized and Cluster-Randomized Crossover Studies

In recent years, the number of studies using a cluster-randomized design has grown dramatically. In addition, the cluster-randomized crossover design has been touted as a methodological advance that can increase efficiency of cluster-randomized studies in certain situations. While the cluster-randomized crossover trial has become a popular tool, standards of design, analysis, reporting and impl...

Cluster-randomized Studies in Educational Research: Principles and Methodological Aspects

An increasing number of studies are being performed in educational research to evaluate new teaching methods and approaches. These studies could be performed more efficiently and deliver more convincing results if they more strictly applied and complied with recognized standards of scientific studies. Such an approach could substantially increase the quality in particular of prospective, two-ar...

Sample size estimation for survival outcomes in cluster-randomized studies with small cluster sizes.

We present a method for computing sample size for cluster-randomized studies involving a large number of clusters with relatively small numbers of observations within each cluster. For multivariate survival data, only the marginal bivariate distribution is assumed to be known. The validity of this assumption is also discussed.

Cluster Unit Randomized Trials

Cluster Randomized Controlled Trial

The high prevalence and diversity of longer-term problems experienced by patients with stroke and their carers has long been recognized, but they remain poorly addressed by existing services. Postdischarge contact with therapy services is associated with improved outcomes. However, these interventions are generally time limited and have little effect on psychosocial outcome. National guidelines...