Suppose you were conducting a survey to try to determine what portion of voters in your town support a particular candidate for mayor. Consider each of the following methods for sampling the voting population of your town. State whether each is likely to produce a representative sample and explain your reasoning.
Call one number from each page of the phone book between noon and 2 p.m.
This does not sample people who do not put their numbers in the phone book.
Also, many people work from noon to 2 p.m. so you would be leaving out an important part of the population.
Survey each person leaving a local grocery store.
What about people that go to different grocery stores?
Survey each person leaving a local movie theater.
Do all of these people have something in common other than the fact that they live in your town?
If so, this is not likely to produce a representative sample.
Walk around downtown and survey every fourth person you see.
Not everyone likes to or has to go downtown.
Could you make a representative sample by surveying a few people from each of the situations described in parts (a) through (d) above? Explain.
This would be closer to a random sample so it is more likely to produce a representative sample.