Balance in cluster randomised trials.

Raab, Gillian and Butcher, Izzy (2001) Balance in cluster randomised trials. Statistics in Medicine, 20 (3). pp. 351-365. ISSN 0277-6715

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This paper explores the role of balancing covariates between treatment groups in the design of cluster randomized trials. General expressions are obtained for two criteria to evaluate designs for parallel group studies with two treatments. The first is the variance of the estimated treatment effect and the second is the extent to which the estimated treatment effect is changed by adjusting for covariates. It is argued that the second of these is more important for cluster randomized trials. Methods of obtaining balanced designs from covariates which are available at the start of a study are proposed. An imbalance measure is used to compare the extent to which designs balance important covariates between the arms of a trial. Several approaches to selecting a well balanced design are possible. A method that randomly selects one member from the class of designs with acceptable bias will allow randomization inference as well as model-based inference. The methods are illustrated with data from a trial of school-based sex education.

Item Type: Article
Print ISSN: 0277-6715
Electronic ISSN: 1097-0258
Uncontrolled Keywords: Covariates; Cluster randomized trials; Estimated treatment effect; Imbalance measure
University Divisions/Research Centres: Faculty of Health, Life & Social Sciences > School of Nursing, Midwifery and Social Care
Dewey Decimal Subjects: 600 Technology > 610 Medicine & health > 610 Medicine & health
300 Social sciences > 310 Statistics
Library of Congress Subjects: R Medicine > R Medicine (General)
H Social Sciences > HA Statistics
Item ID: 1607
Depositing User: RAE Import
Date Deposited: 02 May 2008 14:29
Last Modified: 14 Sep 2012 08:28

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