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Power and Sample Size

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Part of the Methods in Molecular Biology™ book series (MIMB,volume 404)

Abstract

In this chapter, we discuss the concept of statistical power and show how the sample size can be chosen to ensure a desired power. Power is the probability of rejecting the null hypothesis when the null hypothesis is false, that is the probability of saying there is a difference when a difference actually exists. An underpowered study does not have a sufficiently large sample size to answer the research question of interest. An overpowered study has too large a sample size and wastes resources. We will show how the power and required sample size can be calculated for several common types of studies, mention software that can be used for the necessary calculations, and discuss additional considerations.

Key Words

  • Clinically meaningful effect
  • hypothesis test
  • power
  • sample size
  • type I error
  • type II error

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© 2007 Humana Press Inc., Totowa, NJ

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Case, L.D., Ambrosius, W.T. (2007). Power and Sample Size. In: Ambrosius, W.T. (eds) Topics in Biostatistics. Methods in Molecular Biology™, vol 404. Humana Press. https://doi.org/10.1007/978-1-59745-530-5_19

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  • DOI: https://doi.org/10.1007/978-1-59745-530-5_19

  • Publisher Name: Humana Press

  • Print ISBN: 978-1-58829-531-6

  • Online ISBN: 978-1-59745-530-5

  • eBook Packages: Springer Protocols