(Randomized controlled trial or randomized clinical trial) An experiment that uses random assignment to create treatment and control groups so that changes can be inferred or attributed to the experimental treatment.
A study in which the investigators determine and control the conditions of the experiment (see also interventional study).
A study in which the investigator specifies the exposure category for each individual (clinical trial) or community (community trial), then follows the individuals or community to detect the effects of the exposure.
A study in which one treatment is compared to another.
A true experimental study is one in which participants are randomly assigned to groups that experience carefully controlled interventions manipulated by the experimenter according to a strict logic allowing causal inference about the effects of the interventions under investigation. (See also: Quasi-Experimental Study).
Studies in which variables are controlled by the researcher. Because of this control, studies can better provide confirmation of an association between an exposure and an outcome.
A comparative study involving an intervention or manipulation. It is called a trial when human subjects are involved.
