Question

A store manager wants to conduct a survey to determine the average number of items bought by shoppers after
12
:
00
p.m.



Which TWO approaches would BEST obtain a random sample that represents the shoppers?



A.
Obtain the data from each shopper on a Wednesday at
1
:
00
p.m.

B.
Obtain the data from one shopper on each day of the week at
1
:
00
p.m.

C.
Obtain the data from random selected shoppers throughout the week who shop after
12
:
00
p.m.

D.
Obtain the data from each shopper during randomly selected times during the week after
12
:
00
p.m.

E.
Obtain the data from randomly selected shoppers during the same time each day during the week after
12
:
00
p.m.

Answer 1

Correct choices: C and D.

- C selects shoppers at random throughout the week after 12:00 p.m., avoiding time-of-day bias.
- D uses randomly chosen times after 12:00 p.m. and samples shoppers at those times, which also produces a representative sample across different post-noon periods.

Options A, B, and E fix the same time(s) and could produce time-of-day bias.