Statistical Power and the Classical Twin Design

Pak C. Sham*, Shaun M. Purcell, Stacey S. Cherny, Michael C. Neale, Benjamin M. Neale

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Dr Nick Martin has made enormous contributions to the field of behavior genetics over the past 50 years. Of his many seminal papers that have had a profound impact, we focus on his early work on the power of twin studies. He was among the first to recognize the importance of sample size calculation before conducting a study to ensure sufficient power to detect the effects of interest. The elegant approach he developed, based on the noncentral chi-squared distribution, has been adopted by subsequent researchers for other genetic study designs, and today remains a standard tool for power calculations in structural equation modeling and other areas of statistical analysis. The present brief article discusses the main aspects of his seminal paper, and how it led to subsequent developments, by him and others, as the field of behavior genetics evolved into the present era.

Original languageEnglish
Pages (from-to)87-89
Number of pages3
JournalTwin Research and Human Genetics
Issue number2
StatePublished - 1 Apr 2020


  • Twin studies
  • effect size
  • null hypothesis
  • research design
  • statistical power
  • statistical significance
  • type I error
  • type II error


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