Methods at a Glance

 

Trials that Randomize Groups or Deliver Interventions to Groups

Experiments, including clinical trials, differ considerably in the methods used to assign participants to study conditions (or study arms) and to deliver interventions to those participants.

This website provides information related to the design and analysis of experiments in which (1) participants are assigned in groups (or clusters) and individual observations are analyzed to evaluate the effect of the intervention, and (2) participants are assigned individually but receive at least some of their intervention with other participants or through an intervention agent shared with other participants.

This material is relevant for both human and animal studies as well as basic and applied research. And while it is important for investigators to become familiar with the issues presented on this website, it is even more important that they collaborate with a methodologist who is familiar with these issues.

In a group-randomized trial, also called a cluster-randomized trial, groups or clusters are randomized to study conditions, and observations are taken on the members of those groups.  

Learn more about GRTs

In an individually randomized group-treatment trial, also called a partially clustered design, individuals are randomized to study conditions but receive at least some of their intervention with other participants or through an intervention agent shared with other participants.

Learn more about IRGTs


NIH Clinical Trial Requirements


The NIH launched a series of initiatives to enhance the accountability and transparency of clinical research. These initiatives target key points along the entire clinical trial lifecycle, from concept to reporting the results.

Questions?

You may find more answers in the Reference Materials section.

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This page was last updated/reviewed 4/14/2021