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An integrated population-averaged approach to the design, analysis and sample size determination of cluster-unit
John S Preisser1, Mary L Young, Daniel J Zaccaro
1Department of Biostatistics, University of North Carolina School of Public Health, Chapel Hill, North Carolina 27599-7420, USA. jpreisse@bios.unc.edu
Abstract:
While the mixed model approach to cluster randomization trials is relatively well developed, there has been less attention given to the design and analysis of population-averaged models for randomized and non-randomized cluster trials. We provide novel implementations of familiar methods to meet these needs. A design strategy that selects matching control communities based upon propensity scores, a statistical analysis plan for dichotomous outcomes based upon generalized estimating equations (GEE) with a design-based working correlation matrix, and new sample size formulae are applied to a large non-randomized study to reduce underage drinking. The statistical power calculations, based upon Wald tests for summary statistics, are special cases of a general power method for GEE.