HIV/AIDS Glossary

A type of clinical trial in which participants are assigned by chance (randomized) to the arms of the trial (experimental or control arms). Randomization eliminates any potential preference in assigning participants to the arms of the trial and increases the likelihood that the trial arms are comparable overall in terms of general characteristics, such as age or gender, and other factors that might affect the disease or condition being studied. Having arms that are as similar as possible at the start of a clinical trial allows researchers to conclude with a certain level of confidence whether one intervention is better than another at the end of the trial.