Double-blind study
A double-blind study is a study in which neither the subjects nor the researchers conducting the study know who is getting the real treatment and who is getting the placebo. This means that the subjects are less likely to be affected by psychological factors that may make the treatment seem more or less effective. Researchers, on the other hand, are protected from their own pre-conceptions and biases, such as subconsciously looking for "expected" findings or intentionally or unintentionally suggesting "correct" responses to subjects. Controlled, double-blind studies are considered to be the most reliable.