FROM DATA TO DECISION Critical Thinking: What does the survey tell us? Surveys have become an integral part of our lives. Because it is so important that every citizen has the ability to interpret survey results, surveys are the focus of this project. Use the following. A Gallup poll of 3297 U.S. adults showed that 54% of the respondents said it is unlikely that they would use a self-driving car. Analyzing the Data 1. Use the survey results to construct a 95% confidence interval estimate of the percentage of all U.S. adults who say they are unlikely to use self-driving cars. 2. Find the margin of error for this survey. How does it compare to this statement from Gallup: “For results based on the total sample of 3297 U.S. adults, the margin of sampling error is {2 percentage points at the 95% confidence level.”? 3. Explain why or why not an online news website would be justified in publishing this claim: “Most U.S. adults say they are unlikely to use self-driving cars.” 4. Assume that you are an online reporter. Write a description of the survey results for your website. 5. A common criticism of surveys is that they poll only a very small percentage of the population and therefore cannot be accurate. Given that a sample of size 3297 from a population of 256,338,241 adults is a sample that is only 0.001% of the population, is that sample size too small? Write a brief explanation of why the sample size of 3297 is or is not too small. 6. In reference to another survey, the president of a company wrote to the Associated Press about a nationwide survey of 1223 subjects. Here is what he wrote: When you or anyone else attempts to tell me and my associates that 1223 persons account for our opinions and tastes here in America, I get mad as hell! How dare you! When you or anyone else tells me that 1223 people represent America, it is astounding and unfair and should be outlawed. The writer of that letter then proceeds to claim that because the sample size of 1223 people represents 120 million people, his single letter represents 98,000 (120 million divided by 1223) who share the same views. Do you agree or disagree with this claim? Write a response that either supports or refutes this claim. 1. Out-of-class activity Collect sample data, and use the methods of this chapter to construct confidence interval estimates of population parameters. Here are some suggestions for parameters: • Proportion of students at your college who can touch their nose with their tongue • Proportion of students at your college who can raise one eyebrow without raising the other eyebrow • Mean age of cars driven by statistics students and/or the mean age of cars driven by faculty • Mean length of words in New York Times editorials and mean length of words in editorials found in your local newspaper • Proportion of students at your college who can correctly identify the president, vice president, and secretary of state • Proportion of students at your college who are over the age of 18 and are registered to vote • Mean age of full-time students at your college • Mean number of hours that students at your college study each week • Proportion of student cars that are painted white • Proportion of cars that are red Cooperative Group Activities CHAPTER 7 Cooperative Group Activities 369
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