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.
Meurer WJ, Lewis RJ. Cluster Randomized TrialsEvaluating Treatments Applied to Groups. JAMA. 2015;313(20):2068-2069. doi:10.1001/jama.2015.5199