Placebo-controlled trials are necessary to the effectiveness of certain studies. In order to be sure that the drug or device is the factor that is in actuality changing the condition of the patient or just a change of mentality. There are cases where the placebo effect is so powerful that a patient will feel healed or treated, and the use of the drug would be unnecessary. Then in cases where the patients with the placebo do not feel any change but the ones with the real drug do, then researches could know with more confidence the results of their findings.