Question

In double-blind studies neither the test subject or the researcher knows who was given the drug and who was given the control. Why are these studies effective for testing a drug that may elevate mood and relieve feelings of depression?
Since there are two symptoms that are affected, a double-blind study is required.
Doubleblind studies are ways to ensure that only the researcher can figure out who is getting the effective drug
Doubleblind studies are the most economical way to gather results from testing on humans
The patients and researchers are not given this information so they cannot