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Statistical Power and Sample Size Estimation for Headache Research: An Overview and Power Calculation Tools


  • Timothy T. Houle PhD,

  • Donald B. Penzien PhD,

  • Chris K. Houle MSEE

  • From the Center for Pain Studies, Rehabilitation Institute of Chicago/Northwestern University Medical School, Chicago, IL (Dr. Houle); Department of Psychiatry and Human Behavior, and Head Pain Center, University of Mississippi Medical Center, Jackson, MS (Dr. Penzien); and Sargent & Lundy Engineers, LLC (Mr. Houle).

Address all correspondence to Dr. Timothy T. Houle, Center for Pain Studies, 446 E. Ontario, Suite 1011, Chicago, IL 60611.


The present article reviews the concept of statistical power analysis for research designs in headache. First, we present a basic overview of the concepts of statistical hypothesis testing. Then we discuss the elements of power analysis and, where appropriate, we address conventions for power calculations. We offer, for public use, an applied power calculator for two applications that are often encountered in headache research. We intend to help headache researchers design trials with adequate statistical power by offering a conceptual overview and the power calculators. In closing, we briefly address the implications of the present trend toward reporting point estimates of effect sizes with confidence levels.