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.
double - blind studies are ways to ensure that only the researcher can figure out who is getting the effective drug.
double - blind 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 be influenced in reporting the effectiveness.

Explanation:

In double - blind studies, lack of knowledge about who gets the drug or control (by both subjects and researchers) prevents bias. Subjects' expectations (e.g., thinking they got the drug and feeling better) and researchers' interpretations (e.g., unconsciously favoring data from drug - given group) are avoided. This ensures more objective reporting of the drug's effectiveness in elevating mood and relieving depression.

• Option A: The number of symptoms (two here) is not the reason for double - blind. It's about reducing bias.
• Option B: Double - blind is not about the researcher being able to figure out later. It's about preventing bias during the study.
• Option C: Cost - effectiveness (economical) is not the main reason. The key is minimizing bias.

Answer:

D. The patients and researchers are not given this information so they cannot be influenced in reporting the effectiveness.