A SAS macro for constrained randomization of group-randomized designs

M. Ashraf Chaudhary, Lawrence H. Moulton

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Group-randomized study designs are useful when individually-randomized designs either are not possible, or will not be able to estimate the parameters of interest. Group-randomized trials often have small number of experimental units or groups and strong geographically-induced between-unit correlation, thereby increasing the chance of obtaining a "bad" randomization outcome. It has been suggested to highly constrain the design through restriction to those allocations that meet specified criteria based on certain covariates available at the baseline. We describe a SAS® macro that allocates treatment conditions in a two-arm stratified group-randomized design that ensures balance on relevant covariates. The application of the macro is illustrated using two examples of group-randomized designs.

Original languageEnglish (US)
Pages (from-to)205-210
Number of pages6
JournalComputer Methods and Programs in Biomedicine
Issue number3
StatePublished - Sep 2006


  • Constrained randomization
  • SAS
  • Stratified group-randomized trial

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Health Informatics


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