Question

3 The headmaster at a private school wants to

update the student dress code. He wishes to
survey a select group of parents of the students
enrolled at the school to determine their
opinion on the addition of a blazer to the school
uniform. Which method can be used to ensure
an unbiased sample is obtained for the survey?

A All parents attending the next PTO meeting
are surveyed.

B Every fifth person on a list of parent
volunteers is surveyed.

C All parents waiting in the pick-up line after
school are surveyed.

D All parents of students whose birthdays are
on even numbered days are surveyed.

Answer 1

B

Explanation:

A. There will be bias with this solution as parents that attend the PTO meeting will already know the school well, and are likely to sway the vote.

B. Every 5th person creates unbias, as the Headmaster can not pick who to survey from the list. Therefore, I would argue that this is the best way to survey the parents out of the provided options.

C. We can not infer that every parent waits in the pick-up line, and therefore it would be unfair to carry out the data collection knowing that you are going to miss out on parents' opinions.

D. This completely rules out all students with uneven numbered birthdays for no reason, which is an unfair way of carrying out this survey.