An experiment in which subjects are randomly assigned to â€œtreatmentâ€ and â€œcontrolâ€ groups, so ensuring that potentially confounding variables will be uniform across both groups (thereby preventing confounding from distorting the association between treatment and outcome).
Trial where people are put into groups by chance. One group is given the best current treatment or a placebo and their progress is compared with those having the treatment that is being tested. People are usually selected for each group by a computer.
A study in which people are assigned by chance (e.g. flip of a coin) to receive either an experimental treatment or no treatment (e.g. placebo or usual care). People in the study are the same at onset and are cared for in exactly the same way throughout the trial. Any differences between the two groups at the end of the trial can then be attributed to the difference in treatment alone, and not to bias or chance.