Good Clinical Practice (GCP) Practice Exam

Which of the following describes single-blinding?

1. Both subjects and investigators are unaware of treatment assignments

2. Usually refers to the subject(s) being unaware

3. All parties involved are aware of the assignment

4. Only the data analysts are unaware of treatment assignments

The correct answer is: Usually refers to the subject(s) being unaware

Single-blinding typically refers to a study design where at least one party involved in the trial is unaware of the treatment assignments while the other parties might be aware. In most cases, this means that the subjects in the clinical trial do not know which treatment they are receiving, whether it’s a placebo or the active treatment. This design helps to prevent bias in the subjects' reporting of outcomes and their behaviors during the study, ensuring that their perceptions do not influence the results. By keeping the subjects unaware, researchers can obtain more objective data regarding the safety and efficacy of the treatments being tested. The other choices do not accurately describe single-blinding. In double-blinding (the context of option A), both subjects and investigators are kept unaware of the treatment assignments, which helps eliminate bias from both parties. The third option suggests a scenario of no blinding where all parties are aware of the treatment assignments, which does not align with the principle of single-blinding. The last option speaks to data analysts alone remaining unaware, which does not encompass the concept of single-blinding as it relates to the subjects in most clinical trials.