# ch14 - blu03683_ch14.qxd 10/05/2005 06:32 PM Page 707 14...

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Objectives After completing this chapter, you should be able to 1 Demonstrate a knowledge of the four basic sampling methods. 2 Recognize faulty questions on a survey and other factors that can bias responses. 3 Solve problems, using simulation techniques. Outline 14–1 Introduction 14–2 Common Sampling Techniques 14–3 Surveys and Questionnaire Design 14–4 Simulation Techniques 14–5 The Monte Carlo Method 14–6 Summary 14–1 14 Sampling and Simulation CHAPTER

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708 Chapter 14 Sampling and Simulation 14–2 Statistics Today The Monty Hall Problem On the game show Let’s Make A Deal, host Monty Hall gave a contestant a choice of three doors. A valuable prize was behind one door, and nothing was behind the other two doors. When the contestant selected one door, host Monty Hall opened one of the other doors that the contestant didn’t select and that had no prize behind it. (Monty Hall knew in advance which door had the prize.) Then he asked the contestant if he or she wanted to change doors or keep the one that the contestant originally selected. Now the question is, Should the contestant switch doors, or does it really matter? This chapter will show you how you can solve this problem by simulation. For the answer, see Statistics Today—Revisited. 14–1 Introduction Most people have heard of Gallup, Harris, and Nielsen. These and other pollsters gather information about the habits and opinions of the U.S. people. Such survey ±rms, and the U.S. Census Bureau, gather information by selecting samples from well-de±ned popula- tions. Recall from Chapter 1 that the subjects in the sample should be a subgroup of the subjects in the population. Sampling methods often use what are called random numbers to select samples. Since many statistical studies use surveys and questionnaires, some information about these is presented in Section 14–3. Random numbers are also used in simulation techniques. Instead of studying a real- life situation, which may be costly or dangerous, researchers create a similar situation in a laboratory or with a computer. Then, by studying the simulated situation, researchers can gain the necessary information about the real-life situation in a less expensive or safer manner. This chapter will explain some common methods used to obtain samples as well as the techniques used in simulations.
Section 14–2 Common Sampling Techniques 709 14–3 14–2 Common Sampling Techniques In Chapter 1, a population was defned as all subjects (human or otherwise) under study. Since some populations can be very large, researchers cannot use every single subject, so a sample must be selected. A sample is a subgroup oF the population. Any subgroup oF the population, technically speaking, can be called a sample. However, For researchers to make valid inFerences about population characteristics, the sample must be random.

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## ch14 - blu03683_ch14.qxd 10/05/2005 06:32 PM Page 707 14...

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