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A pharmaceutical company is testing a new drug designed to lower blood pressure. They conduct a clinical trial with 200 participants, randomly divided into two groups. Group A receives the new drug, and Group B receives a placebo. Neither the participants nor the administering staff know who is receiving the drug or the placebo. After 8 weeks, the average blood pressure reduction in Group A is 15 mmHg, while in Group B it is 3 mmHg. What is the most significant advantage of using a 'double-blind' protocol in this experiment?
- AIt ensures that all participants have similar initial health conditions.
- BIt reduces the cost of conducting the clinical trial.
- CIt guarantees a larger sample size for statistical significance.
- DIt prevents bias from influencing the results.
Show answer & explanationAnswer & explanation
Correct answer: D. It prevents bias from influencing the results.
A double-blind protocol prevents both the subjects and the researchers from knowing who is in the experimental or control group. This eliminates potential biases, such as the placebo effect being enhanced by subject expectation or researcher observation bias, ensuring a more objective assessment of the drug's true effect.
Why the other options are wrong
- A. Random assignment helps with this, but the double-blind aspect specifically addresses bias, not initial conditions.
- B. Implementing a double-blind study can often be more complex and expensive due to logistical requirements.
- C. Sample size is determined separately, not by the blinding protocol.
Double-Blind Study
An experimental procedure in which neither the subjects nor the experimenters know who is receiving a particular treatment.
- Minimizes bias from participant expectations (placebo effect).
- Minimizes bias from researcher expectations (observer bias).
- Often used in clinical trials for drugs or treatments.
Memory trick: Blinding: 'Blind' to the truth to find the real truth.