Which type of research study is set up so that neither subjects nor investigators know which is the active group and which is receiving a placebo?

a. Double blind

b. Clinical trial

c. Case control

d. Epidemiological

A) Double blind is the research study set up so that neither subjects nor investigators know which is the active group and which is receiving a placebo.

The best answer to the question above would be letter a. A type of research study set up so that neither subjects nor investigators know which is the active group and which is receiving a placebo is a double blind type of research method.