1 Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC 27599, USA 2 Department of Psychiatry, Washington University School of Medicine, St ...

Pilot trials have a key role in preparing for definitive randomized trials, yet determining their sample size remains a common challenge. This article provides practical guidance, methods, and ...

It has long been recognized that sample size calculations for cluster randomized trials require consideration of the correlation between multiple observations within the same cluster. When ...

Power analyses and sample size calculations are important parts of many research projects. Often, before data are even collected, it is necessary to calculate and justify the required sample size for ...

Power analyses and sample size calculations are important parts of many research projects. Often, before data are even collected, it is necessary to calculate and justify the required sample size for ...

Using whole populations for a study is not practical nor feasible. For this reason, when performing a clinical study, a 'sample' is selected from the population and, from the obtained results, we make ...

A sample size with sufficient statistical power is critical to the success of genetic association studies to detect causal genes of human complex diseases. Genome-wide association studies require much ...