When neither researchers nor participants are aware of group assignments, what is this design called?

• A. Double blind
• B. Single blind
• C. Triple blind
• D. Open-label

Answer: (A)

Blinding in trials aims to prevent bias by keeping those involved unaware of which participants receive which intervention. When neither the participants nor the researchers collecting or evaluating data know the assignments, this is a double-blind design. This approach minimizes two main sources of bias: participants’ expectations that could influence their reporting or behavior, and researchers’ expectations that could affect how they administer treatments or judge outcomes. If only the participants are unaware, it’s a single-blind design; if outcome assessors or data analysts are also kept in the dark, it’s often described as triple-blind. If everyone knows the group assignments, it’s an open-label design. In the scenario described, the double-blind setup best fits.