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The Bias Coin Design


  • Carol Sweeney CNM, MS,

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    • Carol Sweeney received her BS in nursing from Washington State University, and her MSN and CNM from the University of Utah. She is currently clinical instructor of nursing in the graduate nurse-midwifery program at the University of Utah College of Nursing.

  • Marlene J. Egger PhD

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    • Marlene J. Egger received her MS and PhD in statistics from Stanford University. She is currently Assistant Professor in the Department of Family and Community Medicine, Division of Biostatistics, University of Utah School of Medicine

University of Utah College of Nursing, 25 South Medical Drive, Salt Lake City, UT 84112.


In clinical research with small sample size, problems can arise in allocating subjects into various treatment groups when they are accessioned into a study over time. The Biased Coin Design (BCD) was designed to overcome the problems of biased or unbalanced treatment groups, while ensuring the advantages of complete randomization. The BCD is discussed, and an example of its use in clinical research is given.