title: [Explanation of samples sizes in current biomedical journals: an irrational requirement].
abstract: OBJECTIVE
  To discuss the theoretical relevance of current requirements for explanations of the sample sizes employed in published studies, and to assess the extent to which these requirements are currently met by authors and demanded by referees and editors.
  
  
  METHODS
  A literature review was conducted to gain insight into and critically discuss the possible rationale underlying the requirement of justifying sample sizes. A descriptive bibliometric study was then carried out based on the original studies published in the six journals with the highest impact factor in the field of health in 2009.
  
  
  RESULTS
  All the arguments used to support the requirement of an explanation of sample sizes are feeble, and there are several reasons why they should not be endorsed. These instructions are neglected in most of the studies published in the current literature with the highest impact factor. In 56% (95%CI: 52-59) of the articles, the sample size used was not substantiated, and only 27% (95%CI: 23-30) met all the requirements contained in the guidelines adhered to by the journals studied.
  
  
  CONCLUSIONS
  Based on this study, we conclude that there are no convincing arguments justifying the requirement for an explanation of how the sample size was reached in published articles. There is no sound basis for this requirement, which not only does not promote the transparency of research reports but rather contributes to undermining it.
authors.affiliation: Vicedirección de Docencia e Investigación, Centro Nacional de Información de Ciencias Médicas, La Habana, Cuba. lcsilva@infomed.sld.cu
authors.forename: Luis Carlos
authors.initials: LC
authors.lastname: Silva Ayçaguer
authors.forename: Patricia
authors.initials: P
authors.lastname: Alonso Galbán
mesh_terms: D010506:Periodicals as Topic; D011643:Publishing / Q000592:standards*; D018401:Sample Size