In a clinical trial, a volunteer is usually assigned a specific study group. Volunteers in one study group may receive an investigational treatment or study drug while other volunteers may receive a placebo or a treatment already available.
A placebo is an inactive product used to assess the experimental treatment’s effectiveness. The participant, physician, and research staff may not know which volunteer receives a placebo and which receives the active treatment.
Not knowing which participants are receiving the active treatment allows the physician and research staff to objectively observe the volunteers during the study. Regardless of which treatment volunteers receive, however, the level of medical attention and care that each receives is the same.