Pragmatic and Group-Randomized Trials in Public Health and Medicine

Online Course

Part 4: Power and Sample Size

Explores power and sample size for group-randomized trials (GRTs) with a focus on:

  • Cornfield's two penalties of extra variation and limited degrees of freedom (df)
  • Strategies to reduce extra variation and increase df
  • The seven steps involved in any power analysis
  • Estimating the intraclass correlation coefficient (ICC)
  • Adaptations required for unbalanced designs

The course also provides an example of a sample size calculation for a simple GRT.

Recorded on September 15, 2016

Interested in more information about power
and sample size for GRTs?

Visit NIH's Research Methods Resources website for a list of publications on sample size estimation methods and a sample size calculator for GRTs. If you'd like a demonstration
of how to use the sample size calculator, check out this Mind the Gap webinar.

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