AP Stats Chapter 4

The web portal AOL places opinion poll questions next to many of its news stories. Simply click your response to join the sample. One of the questions in January 2008 was "Do you plan to diet this year?" More than 30,000 people responded, with 68% saying "Yes." You conclude that

• about 68% of Americans planned to diet in 2008

• the poll used a convenience sample, so the results tell us little about the population of all adults.

• the poll uses voluntary response, so the results tell us little about the population of all adults.

• the sample is too small to draw any conclusions.

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Can changing diet reduce high blood pressure? Vegetarian and low-salt diets are both promising. Men with high blood pressure are assigned at random to four diets: 1) normal diet with unrestricted salt, 2) vegetarian with unrestricted salt, 3) normal with restricted salt, 4) vegetarian with restricted salt. This experiment has

• one factor, the type of diet

• two factors, high blood pressure and type of diet

• two factors, normal/vegetarian diet and unrestricted/restricted salt

• three factors, men, high blood pressure, and type of diet

• four factors, the types of diets being compared

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Suppose that 35% of the registered voters in a state are registered as Republicans, 40% as Democrats, and 25% as Independents. A newspaper wants to select a sample of 1000 registered voters to predict the outcome of the next election. If they randomly select 350 Republicans, randomly select 400 Democrats, and randomly select 250 Independents, did this sampling procedure result in a simple random sample of registered voters from this district?

• Yes, because each registered voter had the same chance of being chosen.

• Yes, because random chance was involved.

• No, because not all registered voters had the same chance of being selected.

• No, because there were a different number of registereed voters selcted from each party.

• No, because not all possible groups of 1000 registered voters had the same chance of being chosen.

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An SRS of 1200 adult Americans is selected and each person is asked the following question: "In light of the huge national deficit should the government at this time spend additional money to establish a national system of health insurance?" Only 39% of those responding answered "Yes." This survey

• is reasonably accurate since it used a large SRS.

• needs to be larger since only about 24 people were drawn from each state.

• probably understates the percent of people who favor a system of national health insurance.

• is very inaccurate but neither understates nor overstates the percent of people who favor a system of national health insurance. Because an SRS was used, the survey is unbiased.

• probably overstates the percent of people who favor a system of national health insurance.

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