Question 17
MediumOriginal questionA principal wants to know the average daily screen time of the 1,200 students in her school. She picks 60 students by drawing names at random from the full roll and finds that they average 3.2 hours a day.
Which of these ways of choosing 60 students would have given the principal a biased sample?
Show the answer and explanation
CorrectNot quiteAnswer D
Correct answer: D
Explanation
A sample is biased when some students are more likely to be chosen in a way linked to what is measured.
Computer-club members likely spend more time on screens, so they would push the estimate up.
Worth noting
Drawing at random within each class is still random; every student has a chance of being picked.
- Concept
- Random and biased samples
- Typical timeTypical
- 120 s
- Your timeYours
- —
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Ten questions from Sampling, Inference & the t-Test, at your own pace.