title: [Comparing two groups of patients].
abstract: In medical research, comparing two groups of patients occurs frequently. The basic principles of comparison and the usual statistical tests--according to the types of variables and the choices of sampling methods--are presented. Elements needed for the computation of the size of a comparative study are given.
authors.affiliation: MCU-PH biostatistiques et informatique médicale, Inserm U444, hôpital Saint-Antoine, Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Carrat
mesh_terms: D006801:Humans; D008432:Mathematical Computing; D012107:Research Design; D018401:Sample Size