A blind experiment is a scientific study in which the participants are unaware of what is being tested or what the outcome is. Synonyms for blind experiment may include masked study, concealed trial, or hidden investigation. Other possible related terms might include double-blind study, where both the participant and the researcher are kept in the dark about the study's purpose, or a placebo-controlled study, in which a control group is given an inert substance as a means of comparison. No matter the term one uses, the purpose of a blind experiment is to eliminate bias and create reliable scientific results.