Association of Clinical Research Professionals (ACRP) Certified Professional Practice Exam

What type of study design allows the study team to know the treatment assignment while the participants do not?

1. Double-blind

2. Open-label

3. Single blind

4. Triple blind

The correct answer is: Single blind

The chosen answer pertains to a study design where the treatment assignment is known to the study team but remains concealed from the participants. This design is commonly referred to as single-blind. In a single-blind study, the researchers or those administering the treatment have knowledge of the treatment allocation, which allows them to monitor adherence to the protocol and manage any potential effects of the treatment that participants might perceive. At the same time, the lack of awareness of the participants regarding their treatment group helps to mitigate biases related to their expectations, thus improving the integrity of the data collected. In contrast, a double-blind study would mean that both the participants and the study team are unaware of the treatment assignments, which further minimizes bias but is not the case in this particular scenario. An open-label study means that both participants and researchers are aware of the treatment assignments, leading to potential biases from both parties. Finally, a triple-blind study adds another layer of blinding, usually involving those analyzing the data, but this level of complexity is not necessary if only the participants are to remain blinded. Ultimately, the single-blind design is specifically structured to protect the study's validity by keeping participants uninformed about their treatment while allowing the study team to remain informed.