Answer:The general principles of the FDA guidance on the choice of control groups in clinical trials as follows:
· Its ability to minimize bias
· Ethical and practical issues associated with its use
· Its usefulness and the quality of inference in particular situations
· Modifications of study design or combinations with other controls that can resolve ethical, practical, or inferential concerns.
Although this guidance is focused primarily on clinical trials intended to assess the efficacy of a treatment, many of the considerations discussed also apply to the assessment of specific safety hypotheses and to safety or efficacy comparisons of two treatments.