The cafeteria chef for a company wants to know about how many of the employees are vegetarians. Which sampling method will result in a sample that is NOT biased?
a) He questions every employee in the advertising department who is exiting a meeting.
b) He obtains a list of employee names and numbers and calls every fifth person on the list.
c) He puts notices in the break rooms asking employees to e-mail him if they are a vegetarian. d) He asks every other employee he sees in the cafeteria for breakfast about food preferences...
d) He asks every other employee he sees in the cafeteria for breakfast about food preferences...