title: The most frequently asked question to a statistician: The sample size.
abstract: The calculation of the sample size needed for a clinical study is the challenge most frequently put to statisticians, and it is one of the most relevant issues in the study design. The correct size of the study sample optimizes the number of patients needed to get the result, that is, to detect the minimum treatment effect that is clinically relevant. Minimizing the sample size of a study has the advantage of reducing costs, enhancing feasibility, and also has ethical implications. In this brief report, I will explore the main concepts on which the sample size calculation is based.
authors.affiliation: Biostatistics Unit, Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy.
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Sormani
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D012107:Research Design; D012108:Research Personnel; D018401:Sample Size; D013223:Statistics as Topic
keywords: Sample size; clinical trials; power