The purpose of double blinding in clinical trials is to:: (A) Achieve comparability between study and control groups, (B) Avoid observer bias, (C) Avoid subject bias, (D) Avoid observer and subject bias
Answer is D. Single blind: Only patients or only investigators are ignorant of assigned treatment.
Double blind: Patients & investigators are ignorant of assigned treatment.
Triple blind: Patients, investigators & data evaluators are ignorant of assigned treatment.