What is a double-blind, double-dummy study?

Answer

Blinding is the act of withholding information from research subjects to provide more accurate results. A double-blind study is a study in which both the participants and the researchers do not know which of the study subjects are in the experimental group. In a double-dummy study, all of the research participants receive a placebo for at least part of the research period. Double-blind, double-dummy studies meet both blinding conditions.

Blinding is designed to prevent the placebo effect. The placebo effect occurs when research subjects expect certain results, such as symptom improvement from a medication, and then experience them when receiving a treatment with no effects. Researchers also experience the placebo effect when they anticipate that research subjects are going respond to a treatment and then see the expected results. When both groups are unsure of exactly what treatment is being given, the reported results more accurately reflect reality.

Double-dummy conditions usually involve giving all of the research subjects both the experimental treatment and the placebo treatment for a portion of the study. Typically, groups alternate between both conditions with researchers ensuring that subjects remain in each group long enough to provide accurate research data. This method further reduces the placebo effect, especially when the pool of research subjects is small, by eliminating personality biases.

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