Question

Syrus and Shantel are researching what types of novels people prefer. They decide to survey people at the mall. Syrus uses systematic sampling and asks every sixth person at the entrance. He finds that 25​% prefer fantasy novels. Shantel uses convenience sampling and asks every person in only one store. She finds that 48​% prefer fantasy novels. Whose inference do you agree​ with? Explain. What mistake might the incorrect friend have​ made?
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Part 1
Whose inference do you agree​ with? Explain.
Syrus
Syrus
Shantel
Shantel

Answer 1

I agree with Syrus.

Reason: Systematic sampling (asking every 6th person at the mall entrance) is much more likely to produce a representative sample of mall visitors than Shantel’s method. Shantel used convenience sampling by surveying only people in one store, which can introduce strong selection bias because customers of that store may have different tastes (for example, the store might attract fans of fantasy).

Mistake Shantel made: using a convenience sample (sampling only one store) so her sample is not representative of the population and likely over- or underestimates the true proportion who prefer fantasy. (As a caveat, systematic sampling can also be biased if the “every 6th” pattern somehow aligns with a pattern in entrants, but it is still preferable to a one-store convenience sample.)