• In a Mobile Banking Study of 2000 adults, 91% prefer using an app for banking instead of going to a physical bank. Good to know for bank officials. • In a Sallie Mae survey of 950 undergraduate students, 53% take online courses. Good to know for college officials. • In a Society for Human Resource Management survey of 3490 human resource professionals, 60% of employers offered telecommuting to employees. Good to know for business owners. • Biometric Security: In a USA Today survey of 510 people, 53% said that we should replace passwords with biometric security, such as fingerprints. Good to know for computer, smartphone, and tablet manufacturers. Because surveys are now so pervasive and extensive, and because they are often accepted without question, we should analyze them by considering issues such as the following: • What method was used to select the survey subjects? • How do we use sample results to estimate values of population parameters? • How accurate are survey sample results likely to be? • Typical media reports about surveys are missing an extremely important element of relevant information. What is usually missing? • How do we correctly interpret survey results? For example, the “biometric security” poll cited above is based on a voluntary response sample (described in Section 1-1), so its fundamental validity is very questionable. The other surveys all involve sound sampling methods, so with these surveys we can proceed to consider the other issues listed above. The preceding chapters focused on methods of descriptive statistics, but in this chapter we begin the study of methods of inferential statistics. The following are the major activities of inferential statistics, and this chapter introduces methods for the first activity of using sample data to estimate population parameters. Chapter 8 will introduce basic methods for testing claims (or hypotheses) about population parameters. Major Activities of Inferential Statistics 1. Use sample data to estimate values of population parameters (such as a population proportion or population mean). 2. Use sample data to test hypotheses (or claims) made about population parameters. Here are the chapter objectives: 7-1 Estimating a Population Proportion • Construct a confidence interval estimate of a population proportion and interpret such confidence interval estimates. • Identify the requirements necessary for the procedure that is used, and determine whether those requirements are satisfied. • Develop the ability to determine the sample size necessary to estimate a population proportion. 7-2 Estimating a Population Mean • Construct a confidence interval estimate of a population mean, and be able to interpret such confidence interval estimates. • Determine the sample size necessary to estimate a population mean. Chapter Objectives 311 CHAPTER OBJECTIVES >>>
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