Understanding statistical power

B. J. Norton, M. J. Strube

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


This article provides an introduction to power analysis so that readers have a basis for understanding the importance of statistical power when planning research and interpreting the results. A simple hypothetical study is used as the context for discussion. The concepts of false findings and missed findings are introduced as a way of thinking about type I and type II errors. The primary factors that affect power are described and examples are provided. Finally, examples are presented to demonstrate 2 uses of power analysis, 1 for prospectively estimating the sample size needed to insure finding effects of a known magnitude in a study and 1 for retrospectively estimating power to gauge the likelihood that an effect was missed.

Original languageEnglish
Pages (from-to)307-315
Number of pages9
JournalJournal of Orthopaedic and Sports Physical Therapy
Issue number6
StatePublished - 2001


  • Effect size
  • Power analysis


Dive into the research topics of 'Understanding statistical power'. Together they form a unique fingerprint.

Cite this