Background Studies involving clustering effects are common, but there is little consistency in
their analysis. Various analytical methods were compared for a factorial cluster randomized …

Community intervention trials are often characterized by the allocation of intact social units to
different intervention groups. The assessment of adequate sample size for such trials must …

Background: The use of cluster randomized trials (CRTs) is increasing, along with the variety
in their design and analysis. The simplest approach for their sample size calculation is to …

Cluster randomized trials, where individuals are randomized in groups are increasingly
being used in healthcare evaluation. The adoption of a clustered design has implications for …

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 …

Background A recently developed two-step method provides an alternative to single-step
methods in the analysis of cluster randomized trials (CRTs). This method, called the …

There is currently a lot of interest in pilot studies conducted in preparation for randomised
controlled trials. This paper focuses on sample size requirements for external pilot studies …

Scientists often use randomized controlled trials to compare a newly developed treatment to
the existing one, or to a placebo. Patients are randomly assigned to a treatment, and they …

There is increasing recognition of the critical role of intracluster correlations of health
behavior outcomes in cluster intervention trials. This study examines the estimation …

Background In cluster randomized trials, patients are typically recruited after clusters are
randomized, and the recruiters and patients may not be blinded to the assignment. This …