A volunteer sample is a kind of convenience sample in which participants select themselves to participate. On August 19, 2005, USA Today published an online poll on
its Website asking this question about U.S. college football: “Who is your pick to win the ACC conference this year?” Eight options – seven universities, including top vote-getters Virginia Techn and Miami, as well as an ‘other’ category – were provided.
a. Describe the typical person who might volunteer to be in this sample. Why might this sample be biased, even with respect to the population of U.S. college football fans?
b. Why might external validity or generalization be limited in this sample?
c. Indicate at least one other problem with this poll that you didn’t describe in
parts a or b.
4. For each of the following hypothetical scenarios, state what type of selection is being used to create a sample for the study. Briefly explain your answer too.
a. For a study of stress levels in Fortune 500 company presidents, 25 presidents over age 60 and 25 under age 60 were chosen; every president in a given age category had an equal chance of being chosen for his or her age category.
b. A study of the services offered by counseling centers at American universities examined 20 universities; every American university had an equal chance of being in the study.
c. A study of cell phone usage recruited participants by including an invitation to participate in their cell phone bills.
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