Problem-Solving and Data AnalysisVery hardWhat reduces a margin of error
Problem-Solving and Data Analysis practice question
A poll of 1,000 randomly selected voters reports a margin of error of 3 percentage points. Which of the following changes would most reduce the margin of error?
- A. Polling a random sample of 4,000 voters instead of 1,000Correct
- B. Polling a random sample of 250 voters instead of 1,000
- C. Conducting the same poll on a different day
- D. Asking each of the 1,000 voters more questions
Answer: A. Polling a random sample of 4,000 voters instead of 1,000
The margin of error shrinks as the sample size grows.
Why the other answers are wrong
- B. Polling a random sample of 250 voters instead of 1,000
- A smaller sample increases the margin of error.
- C. Conducting the same poll on a different day
- The day does not change the sampling variability.
- D. Asking each of the 1,000 voters more questions
- More questions do not make the estimate of any one answer more precise.
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