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JAMA Guide to Statistics and Methods |

Cluster Randomized Trials Evaluating Treatments Applied to Groups

William J. Meurer, MD, MS1; Roger J. Lewis, MD, PhD2,3,4,5
[+] Author Affiliations
1Department of Emergency Medicine, University of Michigan, Ann Arbor
2Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance, California
3Los Angeles Biomedical Research Institute, Torrance, California
4David Geffen School of Medicine at University of California, Los Angeles
5Berry Consultants, Austin, Texas
JAMA. 2015;313(20):2068-2069. doi:10.1001/jama.2015.5199.
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This Guide to Statistics and Methods describes the reasons for using cluster randomization in a clinical trial and how to analyze and interpret the results from a trial that did.

Sometimes a new treatment is best introduced to an entire group of patients rather than to individual patients. Examples include when the new approach requires procedures be followed by multiple members of a health care team or when the new technique is applied to the environment of care (eg, a method for cleaning a hospital room before it is known which patient will be assigned the room). This avoids confusion that could occur if all caregivers had to keep track of which patients were being treated the old way and which were being treated the new way.

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