group-randomized trial
a research design in which groups of individuals are randomly assigned to treatment conditions or control conditions. In educational or organizational settings, for example, a group-randomized trial could be used to study classrooms or departments, evaluating the data by means of hierarchical linear modeling and similar analyses that take the larger group membership (e.g., classroom, department) into account. It is similar to a randomized clinical trial but distinct in assigning intact clusters of participants, rather than individual participants, to the specific conditions. Also called cluster-randomized trial.