Sample size calculations for cluster randomised controlled trials with a fixed number of clusters
Open Access
- 30 June 2011
- journal article
- research article
- Published by Springer Science and Business Media LLC in BMC Medical Research Methodology
- Vol. 11 (1), 102
- https://doi.org/10.1186/1471-2288-11-102
Abstract
Cluster randomised controlled trials (CRCTs) are frequently used in health service evaluation. Assuming an average cluster size, required sample sizes are readily computed for both binary and continuous outcomes, by estimating a design effect or inflation factor. However, where the number of clusters are fixed in advance, but where it is possible to increase the number of individuals within each cluster, as is frequently the case in health service evaluation, sample size formulae have been less well studied.Keywords
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