Phenomenon in which a patient experiences an improvement (or apparent improvement) in a medical condition simply as the result of receiving some sort of treatment — not because of the effectiveness of the treatment itself. Placebo effects are common and can make it difficult to evaluate new medical treatments because even ineffective treatments may appear helpful. To account for the placebo effect, many clinical trials compare a control group receiving a placebo to an experimental group receiving a new treatment. To learn more, visit our side trip Fair tests in the field of medicine.
→ → placebo effect