Cluster-randomized controlled trials: a tutorial

This tutorial focuses on cluster-randomized controlled trials (cluster-RCTs). What cluster-RCTs are, why they might be used, and how to include data from cluster-RCTs in systematic reviews.

What is a cluster-randomized controlled trial?

In most RCTs, individuals are randomly assigned to intervention groups. In a cluster-RCT, groups of individuals (e.g., schools, communities, or clinics) are randomized to intervention groups.