title: [On the impact of sample size calculation and power in clinical research].
abstract: The aim of a clinical trial is to judge the efficacy of a new therapy or drug. In the planning phase of the study, the calculation of the necessary sample size is crucial in order to obtain a meaningful result. The study design, the expected treatment effect in outcome and its variability, power and level of significance are factors which determine the sample size. It is often difficult to fix these parameters prior to the start of the study, but related papers from the literature can be helpful sources for the unknown quantities. For scientific as well as ethical reasons it is necessary to calculate the sample size in advance in order to be able to answer the study question.
authors.affiliation: Horten-Zentrum für praxisorientierte Forschung und Wissenstransfer, Universitätsspital Zürich.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Held
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use; D015982:Bias; D001794:Blood Pressure / Q000187:drug effects; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D016001:Confidence Intervals; D015507:Drugs, Investigational / Q000627:therapeutic use; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D012107:Research Design / Q000706:statistics & numerical data*; D018401:Sample Size
chemical_list: D000959:Antihypertensive Agents; D015507:Drugs, Investigational
keywords: Fallzahlplanung; Konfidenzintervall; Therapieeffekt; calcul de la taille de l'un échantillon; confidence interval; effet d'un traitement; intervalle de confiance; sample size calculation; signification statistique; statistical significance; statistische Signifikanz; treatment effect