PURPOSE Researchers who conduct cluster-randomized studies must account for
clustering during study planning; failure to do so can result in insufficient study power. To …

BACKGROUND Primary care research often involves clustered samples in which subjects
are randomized at a group level but analyzed at an individual level. Analyses that do not …

Studies in which data from multiple patients are collected per clinician or per practice are
becoming common in primary care research, particularly with the increase of studies …

Objectives: Cluster randomised trials, in which groups of individuals are randomised, are
increasingly being used in the health field. Adopting a clustered approach has implications …

OBJECTIVE: Simple guidelines for calculating efficient sample sizes in cluster randomized
trials with unknown intraclass correlation (ICC) and varying cluster sizes. METHODS: A …

OBJECTIVE: To provide information concerning the magnitude of the intraclass correlation
coefficient (ICC) for cluster-based studies set in primary care. STUDY DESIGN AND …

Background. Cluster randomized controlled trials increasingly are used to evaluate health
interventions where patients are nested within larger clusters such as practices, hospitals or …

Background Increasingly, researchers are recognizing that there are many situations where
the use of a cluster randomized trial may be more appropriate than an individually …

Cluster randomized trials (CRTs) are increasingly used to evaluate the effectiveness of
health‐care interventions. A key feature of CRTs is that the observations on individuals …

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