Problem-Solving and Data AnalysisHardWhy participants are not told their group
Problem-Solving and Data Analysis practice question
In a trial of a new headache tablet, half the participants receive the tablet and half receive a placebo that looks identical. Participants are not told which they have received. What is the main reason for keeping this information from them?
- A. So that participants' expectations do not influence how they report their headaches.Correct
- B. To reduce the cost of running the trial.
- C. To make the sample of participants random.
- D. To increase the number of participants.
Answer: A. So that participants' expectations do not influence how they report their headaches.
People who know they have the real tablet may expect relief and report it; those who know they have a placebo may not. Hiding the assignment keeps expectation from distorting the results.
Why the other answers are wrong
- B. To reduce the cost of running the trial.
- Concealing the assignment doesn't affect cost.
- C. To make the sample of participants random.
- Randomness comes from how participants are selected and assigned, not from what they are told.
- D. To increase the number of participants.
- Blinding doesn't change how many people take part.
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