Skip to main content

Double-blind comparative study

In this type of study, two groups of subjects receive a treatment. One group receives an untested or new drug, and the other group receives an older drug about which more is typically known. Individuals in both groups don't know what type of treatment they are getting. Furthermore, the researchers administering the treatments are also kept in the dark about which group is receiving which treatment (making it a "double-blind" experiment). This last part is important, because it prevents the researchers from unintentionally tipping off the study participants, or unconsciously biasing their evaluation of the results. The purpose of this kind of study is to eliminate the power of suggestion.

Such studies are especially useful in determining whether a new treatment offers any advantages over an older one. For statistical reasons, they are not quite as good at proving whether a treatment is effective as a double-blind placebo-controlled study , the best and most reliable form of research.

A good double-blind study should enroll at least 100 people, preferably as many as 300. Dramatically effective treatments can prove themselves in somewhat smaller trials; however, research involving 30 or fewer people generally doesn't prove anything at all.

The health information in this Health Library is provided by a third party. TriStar Health does not in any way create the content of this information. It is provided solely for informational purposes. It does not constitute medical advice and is not intended to be a substitute for proper medical care provided by a physician. Always consult with your doctor for appropriate examinations, treatment, testing, and care recommendations. Do not rely on information on this site as a tool for self-diagnosis. If you have a medical emergency, call 911.