Cluster randomized trials and statistical power
The CRT can be a potent tool, however it is not without flaws. As with an individually randomized trial, it often requires a large sample size (i.e. many clusters) to achieve adequate levels of power for its results. Existing formulas to estimate power for a study design frequently rely on simplifications of the study design. Addressing common challenges that researchers face when calculating power such as variability in cluster sizes and uncertainty in between-cluster variability our goal is to illustrate how these features affect power and to show the utility of a simulation-based power calculation methodology.
Using R and the clusterPower package, we conducted a simulation study to quantify how between-cluster variance, treatment effects, number of clusters, and variability in cluster size can influence statistical power of a study. From this study, we derived concrete guidelines that can assist in the design phase of future CRTs, whether for testing a vaccine in Thailand or legislation in America.
Learning Areas:Biostatistics, economics
Conduct evaluation related to programs, research, and other areas of practice
Explain the design of cluster-randomized trials Discuss the usage of cluster randomized trials Assess the impact of selected variables on the cluster-randomized trial's power
Keyword(s): Methodology, Statistics
Qualified on the content I am responsible for because: I am a research assistant studying cluster-randomized trials. I am well-versed in the literature pertaining this subject and have recreated reports using this study design in statistical simulations. I am currently in the process of writing a paper illustrating my findings to be submitted for publication in the near future.
Any relevant financial relationships? No
I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.