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Problem-Solving and Data AnalysisMediumChoosing a representative sample

Problem-Solving and Data Analysis practice question

A council wants to estimate the proportion of all residents who would use a new evening bus. Which sampling method is most likely to give an unbiased estimate?

  1. A. Selecting 400 residents at random from the electoral register and contacting eachCorrect
  2. B. Surveying 400 people waiting at the bus station one evening
  3. C. Posting a poll on the bus company's website
  4. D. Surveying 400 residents of the streets nearest the proposed route

Answer: A. Selecting 400 residents at random from the electoral register and contacting each

A random draw from the full register gives every resident an equal chance.

Why the other answers are wrong

B. Surveying 400 people waiting at the bus station one evening
People at the bus station are far more likely than average to want buses.
C. Posting a poll on the bus company's website
Website visitors self-select and are likely bus users.
D. Surveying 400 residents of the streets nearest the proposed route
Residents near the route have a stronger interest than the town as a whole.

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