title: [Aspects of sample size determination and power calculation illustrated on examples from rehabilitation research].
abstract: Often it is reported in medical studies that an expected effect could not be detected. This may be the case if the sample size had been too small to detect an effect which actually exists. This often is due to the fact that sound sample size estimation had been omitted prior to the study outset. As a result, it is not known how many persons should have been involved in the study to detect this effect if present. On the other hand, if sample size estimation has not been realized, more persons than needed might be included in the study. This is problematic for economic and in particular for ethical reasons. The aim of this paper is to point out the principles of sample size estimation as well as to emphasize its importance not only in general but also in medical rehabilitation research.
authors.affiliation: AG Epidemiologie & International Public Health, Fakultät für Gesundheitswissenschaften, Universität Bielefeld. marcus.kutschmann@uni-bielefeld.de
authors.forename: M
authors.initials: M
authors.lastname: Kutschmann
authors.forename: R
authors.initials: R
authors.lastname: Bender
authors.forename: U
authors.initials: U
authors.lastname: Grouven
authors.forename: G
authors.initials: G
authors.lastname: Berg
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003625:Data Collection / Q000706:statistics & numerical data; D006801:Humans; D015233:Models, Statistical; D012046:Rehabilitation / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012107:Research Design; D018401:Sample Size