Commentary
Sample size calculations for cluster randomised controlled trials with a fixed number of clusters
BMC Medical Research Methodology 2011, 11:102 doi:10.1186/1471-2288-11-102
Commentary
Commentary
BMC Medical Research Methodology 2011, 11:102 doi:10.1186/1471-2288-11-102
Further early references to sample sizes with fixed number of clusters
Michael Campbell (2011-09-12 16:34) University of Sheffield
Hemming et al (2011) give a useful review of sample size calculations with a fixed number of clusters. As they acknowledge their equations (17) to (19) are derived from Donner and Klar (200). I would like to point out the issue of fixed number of clusters was also discussed by Campbell (2000) that the authors’ equation (13) was first given as equation (2) in that paper and as equation (9.7) in Machin and Campbell (2005).
Mike Campbell
References
Campbell MJ Cluster randomized trials in general (family) practice research. Statistical Methods in Medical Research 2000, 9; 81-94
Donner A and Klar N. Design and analysis of cluster randomized trials. London, Arnold 2000
Machin D and Campbell MJ Design of Studies for Medical Research. Chichester, John Wiley and Sons Ltd, 2005
Competing interests
None
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