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Sample Size in Epidemiologic Studies

  1. Guanghan Liu

Published Online: 15 JUL 2005

DOI: 10.1002/0470011815.b2a03134

Encyclopedia of Biostatistics

Encyclopedia of Biostatistics

How to Cite

Liu, G. 2005. Sample Size in Epidemiologic Studies. Encyclopedia of Biostatistics.

Author Information

  1. Merck Research Laboratories, West Point, PA, USA

Publication History

  1. Published Online: 15 JUL 2005


This article provides a broad overview of sample size determination methods for epidemiologic studies. Concepts related to sample size and power calculations are introduced. Formulas for sample size calculations are given for cohort and case–control (unmatched or matched) studies with binomial and Poisson outcomes. Methods for sample size calculations in survival studies and longitudinal studies are also presented. Factors that may affect the sample size and study power are discussed. A brief review of the computational methods and software packages commonly used for sample size calculations is also provided.


  • power;
  • precision;
  • cohort studies;
  • case–control studies;
  • confounding variables;
  • survival studies;
  • longitudinal studies