DAE

Abstract

Cluster randomization trials are those that randomize intact social units or clusters of individuals to different intervention groups. Such trials have been particularly widespread in the evaluation of educational programs and innovations in the provision of health care. This talk will deal with basic issues that must be considered when investigators first consider adopting a cluster randomization trial. Foremost among these is the need to justify the choice of this design given its statistical inefficiency relative to an individually randomized design. The role of matching and stratification in the design of a cluster trial ,and the reasons why many such trials are underpowered, will also be discussed.