title: Understanding type I and type II errors, statistical power and sample size.
abstract: The results of a clinical trial may be subject to random error because of the variability in the measured data, which arises purely by chance. There are two types of random error - type I error and type II error. In this study, type I and type II errors are explained, and the important concepts of statistical power and sample size estimation are discussed.
  
  
  CONCLUSIONS
  The most important way of minimising random errors is to ensure adequate sample size; that is, a sufficient large number of patients should be recruited for the study.
authors.affiliation: Sidra Medical and Research Centre, Doha, Qatar.|Royal Manchester Children's Hospital, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK.
authors.forename: Anthony K
authors.identifier: http://orcid.org/0000-0001-5418-3728
authors.initials: AK
authors.lastname: Akobeng
mesh_terms: D018401:Sample Size; D013223:Statistics as Topic
keywords: Power; Sample size; Type I error; Type II error