A study in which the participants are assigned by chance to separate groups that compare different treatments. Neither the researchers nor the participants can choose which group they may join. Using chance to assign people to groups means that the groups can be compared objectively. At the start of the trial, it is not known which treatment is best. The patient can choose to be part of a randomized trial — or not.
Read more about clinical trials.
Audio contributed by: Marisa Weiss, M.D.