In cluster-randomized trials, groups or clusters of individuals, rather than individuals themselves, are randomly allocated to intervention or control. In this article, we describe a new command, ccrand, that implements a covariate-constrained randomization procedure for cluster-randomized trials. It can ensure balance of one or more baseline covariates between trial arms by restriction to allocations that meet specified balance criteria. We provide a brief overview of the theoretical background, describe ccrand and its options, and illustrate it using an example.
CarterB. R., and HoodK.2008. Balance algorithm for cluster randomized trials. BMC Medical Research Methodology8: 65.
2.
ChaudharyM. A., and MoultonL. H.2006. A SAS macro for constrained randomization of group-randomized designs. Computer Methods and Programs in Biomedicine83: 205–210.
3.
DonnerA., and KlarN.2000. Design and Analysis of Cluster Randomization Trials in Health Research.London: Arnold.
4.
Dos Santos SilvaI., ed. 1999. Cancer Epidemiology: Principles and Methods.Geneva: World Health Organization.
IversN. M., HalperinI. J., BarnsleyJ., GrimshawJ. M., ShahB. R., TuK., UpshurR., and ZwarensteinM.2012. Allocation techniques for balance at baseline in cluster randomized trials: A methodological review. Trials13: 120.
7.
IversN. M., TaljaardM., DixonS., BennettC., McRaeA., TalebanJ., SkeaZ., BrehautJ. C., BoruchR. F., EcclesM. P., GrimshawJ. M., WeijerC., ZwarensteinM., and DonnerA.2011. Impact of CONSORT extension for cluster randomised trials on quality of reporting and study methodology: Review of random sample of 300 trials, 2000-8. British Medical Journal343(d5886): 1–14.
