There are several types of clinical trial designs: randomised or non-randomised controlled trials, single or double blinded trials, and superiority or non-inferiority trials.
Blinding is a procedure in which one or more parties in a trial are kept unaware of which treatments participants have received during a clinical trial.
Phase II clinical studies, or proof of concept studies, begin to test the effect of a medicine on the target disease in humans. These studies are usually run as double-blinded, randomised studies in multiple sites.
There are several kinds of bias that may occur in clinical trials, including selection, measurement, and publication bias. Statistics are used in clinical trials in order to avoid or correct these biases.