In a clinical research study, the treatment is changed during the trial. Only the nurse administering the treatment knows about the change, while the participant is unaware of it. Which type of study design is this?

1. A

   Open-label study.

2. B

   Triple-blind study

3. C

   Single-blind study

4. D

   Double-blind study

Appeared in: AIIMS M.Sc. Nsg Entrance exam-2026

Explanation

• In a single-blind study, the trial is designed so that only one party, typically the participant, is unaware of the treatment allocation.
• The scenario describes the participant being unaware while the nurse (the investigator/administrator) is aware of the treatment.
• This method helps to control for the placebo effect, where a participant's belief in the treatment can influence the outcome.
• The key differentiator is that the investigator is not blinded, unlike in double-blind or triple-blind studies.

Why Other Options Were Wrong

• Option A: In an open-label (or open) trial, both the participant and the investigator know the treatment being administered. This is the opposite of the scenario described.
• Option B: In a triple-blind study, the participant, the investigator (nurse), and the data analyst are all unaware of the treatment allocation. This is a much higher level of blinding than described.
• Option D: In a double-blind study, both the participant and the investigator (the nurse) are unaware of the treatment allocation. The question explicitly states the nurse knows the treatment.

Related Visual

• Visual 1: Diagram: A flowchart illustrating the four types of blinding (Open-label, Single-blind, Double-blind, Triple-blind) and showing which parties (Participant, Investigator, Analyst) are aware or blinded in each type. This visual would clearly map the scenario in the question to the 'Single-blind' category.

Clinical Relevance

• Nursing practice connection: Knowing Blinding in Clinical Research Study Designs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Understanding blinding is fundamental for nurses involved in research to ensure they maintain the integrity of the study protocol and prevent introducing bias.
• As a patient advocate, a nurse must understand the study design to properly manage patient care and answer questions without unblinding the participant or compromising the study.
• What if? If the question stated that neither the nurse nor the participant knew the treatment, the correct answer would become Double-blind study. This design is superior for minimizing both performance bias (from the nurse) and expectation bias (from the participant).

How to Approach the Question

• First, identify the key roles mentioned in the question: the 'participant' and the 'nurse administering the treatment' (the investigator).
• Next, determine the state of knowledge for each role. The participant is 'unaware' (blinded). The nurse 'knows' (is not blinded).
• Recall the definitions of the different blinding types: Single-blind (participant blind), Double-blind (participant and investigator blind), Triple-blind (participant, investigator, and analyst blind), and Open-label (no one is blind).
• Compare the pattern from the question (Participant=Blind, Investigator=Aware) to the definitions.
• The pattern perfectly matches the definition of a 'Single-blind study', making it the correct answer.

Concept Tested & Keywords

• Concept Tested: Blinding in Clinical Research Study Designs
• Stem keywords: clinical research study, nurse administering, participant unaware
• Lead-in keywords: Which type of study design
• Clinical cues: The key information is the distribution of knowledge: the nurse knows, but the participant does not.

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