Randomized, controlled trials are experimental studies in which subjects are randomly allocated to receive or not receive the therapy or intervention under study. Subjects are randomly assigned to 2 study groups, where one group receives the treatment being investigated and the control group usually receives a placebo. Random assignment is the most important aspect of this study design. Randomization reduces the potential for confounding by ensuring that chance variation is the only threat to the comparability of the study groups. The Randomized, controlled trials is generally considered best study designs because the process of random allocation allows for comparability of the study groups and eliminates many types of selection bias. This type of design is often blinded or masked meaning that the investigator or subject is unaware of the subject’s treatment assignment. While double-blinded means neither the investigator nor the subject is aware of the treatment assignment of the subject, this will help to eliminate concerns about information bias. The ethics of conducting a randomized controlled trial must be considered before starting the trial. If a treatment is already believed to be in the patients’ best interests, it would be unethical to withhold the therapy for a control group, as a result, it may be impossible to evaluate it in a randomized, controlled trials.