A menu-driven facility for sample-size calculations in cluster randomized controlled trials
Abstract. We introduce the Stata menu-driven command clustersampsi, which
calculates sample sizes, detectable differences, and power for cluster randomized
controlled trials. The command permits continuous, binary, and rate outcomes
(with normal approximations) for comparisons of two-sided tests in two equal-sized
arms. The command allows for specification of the number of clusters available, or
the cluster size, or the average cluster size along with an estimate of the variation
of cluster sizes. When the number of clusters available is insufficient to detect
the required difference at the prespecified power, clustersampsi will return the
minimum number of clusters required under the prespecified design along with the
minimum detectable difference and maximum achievable power (both for the prespecified
number of clusters). Cluster heterogeneity can be parameterized by using
either the intracluster correlation or the coefficient of variation. The command is
illustrated via examples.
View all articles by these authors:
Karla Hemming, Jen Marsh
View all articles with these keywords:
clustersampsi, sample size, cluster randomized controlled trials, minimum detectable difference, maximum achievable power
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