Which of these samples is most likely to be biased?

Every 50th name on the city's voter list, to estimate adults' agesCorrect answerYour answerMembers of a gym, to estimate how much the adults of a city exerciseCorrect answerYour answerHouseholds drawn by lottery from all wards, to estimate family sizeCorrect answerYour answerStudents picked at random from every class, to estimate study hoursCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

A sample is representative when every part of the population has a fair chance of being in it.
Gym members exercise more than most adults, so they would overstate the city's exercise: a biased sample.

Worth noting

Every 50th voter is a systematic sample from a list of all adults, which is fair.

Concept: Representative and biased samples
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsPopulation and sample

Practise this chapter →

Ten questions from Sampling, Inference & the t-Test, at your own pace.

Which of these samples is most likely to be biased?

Explanation