chapter  1
Pages 8

The past two decades have seen increasing acceptance that decisions regarding major public health interventions or clinical treatments should be based on careful review of the evidence from rigorously conducted studies to analyse the benefi ts and adverse effects of the proposed interventions. Resources for health care are limited even in the industrialised countries and may be severely limited in developing countries. Rational policy making requires that the limited resources available should be used to provide interventions that have been proven to be effective and cost-effective. This book focuses on the collection of evidence of effectiveness and in particular the use of cluster randomised trials to measure the population-level effects of interventions delivered to groups of individuals.