Clinical trial
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Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments and known interventions that warrant further study and comparison. Clinical trials generate data on dosage, safety and efficacy. They are conducted only after they have received health authority/ethics committee approval in the country where approval of the therapy is sought. These authorities are responsible for vetting the risk/benefit ratio of the trial—their approval does not mean the therapy is 'safe' or effective, only that the trial may be conducted.
Edward Jenner vaccinating James Phipps, a boy of eight, on 14 May 1796. Jenner failed to use a control group.
Austin Bradford Hill was a pivotal figure in the modern development of clinical trials.
Timeline of various approval tracks and research phases in the US
Scientific control
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A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements. Scientific controls are a part of the scientific method.
Take identical growing plants (Argyroxiphium sandwicense) and give fertilizer to half of them. If there are differences between the fertilized treatment and the unfertilized treatment, these differences may be due to the fertilizer as long as there weren't other confounding factors that affected the result. For example, if the fertilizer was spread by a tractor but no tractor was used on the unfertilized treatment, then the effect of the tractor needs to be controlled.