The Design of Cluster Randomized Crossover Trials

• Published in: Journal of educational and behavioral statistics Vol. 36; no. 4; pp. 472 - 490
• Main Authors: Rietbergen, Charlotte, Moerbeek, Mirjam
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.08.2011; American Educational Research Association
• Subjects: Breakfasts; Budget allocation; Cluster analysis; Control Groups; Cross over studies; Data models; Design efficiency; Design of experiments; Efficiency; Estimators; Experimental Groups; Experimentation; Intervention; Medical treatment; Random allocation; Research Design; Sample size; Statistical Analysis; Statistical methods; Statistical variance; cluster randomized crossover design; optimal allocation; statistical efficiency
• ISSN: 1076-9986; 1935-1054
• DOI: 10.3102/1076998610379136

The inefficiency induced by between-cluster variation in cluster randomized (CR) trials can be reduced by implementing a crossover (CO) design. In a simple CO trial, each subject receives each treatment in random order. A powerful characteristic of this design is that each subject serves as its own control. In a CR CO trial, clusters of subjects are randomly allocated to a sequence of interventions. Under this design, each subject is either included in only one of the treatment periods (CO at cluster level) or in both periods (CO at subject level). In this study, the efficiency of both CR CO trials relative to the CR trial without CO is demonstrated. Furthermore, the optimal allocation of clusters and subjects given a fixed budget or desired power level is discussed.