A political scientist wants to predict how the residents of New Jersey will react to a new bill. Which study design will provide the most reliable results?
A) Mailing a questionnaire to each of 200 randomly selected residents of NJ
B) Surveying a group of 300 randomly selected NJ residents
C) Interviewing a group of randomly selected students from a NJ public university
D) Surveying 1500 randomly selected US residents
The answer is B, but why wouldn’t it be A?