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Lecture Statistical techniques in business and economics (14/e): Chapter 8 - Lind, Marchal, Wathen

Chapter 8 - Sampling methods and the central limit theorem. When you have completed this chapter, you will be able to: Explain why a sample is the only feasible way to learn about a population, describe methods to select a sample, define and construct a sampling distribution of the sample mean, explain the central limit theorem, use the central limit theorem to find probabilities of selecting possible sample means from a specified population. | Sampling Methods and the Central Limit Theorem Chapter 8 GOALS Explain why a sample is the only feasible way to learn about a population. Describe methods to select a sample. Define and construct a sampling distribution of the sample mean. Explain the central limit theorem. Use the central limit theorem to find probabilities of selecting possible sample means from a specified population. Probability Sampling Why Sample the Population? To contact the whole population would be time consuming. The cost of studying all the items in a population may be prohibitive. The physical impossibility of checking all items in the population. The destructive nature of some tests. The sample results are adequate. What is a Probability Sample? A probability sample is a sample selected such that each item or person in the population being studied has a known likelihood of being included in the sample. Four Most Commonly Used Probability Sampling Methods Simple Random Sample Systematic Random . | Sampling Methods and the Central Limit Theorem Chapter 8 GOALS Explain why a sample is the only feasible way to learn about a population. Describe methods to select a sample. Define and construct a sampling distribution of the sample mean. Explain the central limit theorem. Use the central limit theorem to find probabilities of selecting possible sample means from a specified population. Probability Sampling Why Sample the Population? To contact the whole population would be time consuming. The cost of studying all the items in a population may be prohibitive. The physical impossibility of checking all items in the population. The destructive nature of some tests. The sample results are adequate. What is a Probability Sample? A probability sample is a sample selected such that each item or person in the population being studied has a known likelihood of being included in the sample. Four Most Commonly Used Probability Sampling Methods Simple Random Sample Systematic Random Sampling Stratified Random Sampling Cluster Sampling Simple Random Sample and Systematic Random Sampling Simple Random Sample: A sample selected so that each item or person in the population has the same chance of being included. EXAMPLE: A population consists of 845 employees of Nitra Industries. A sample of 52 employees is to be selected from that population. The name of each employee is written on a small slip of paper and deposited all of the slips in a box. After they have been thoroughly mixed, the first selection is made by drawing a slip out of the box without looking at it. This process is repeated until the sample of 52 employees is chosen. Systematic Random Sampling: The items or individuals of the population are arranged in some order. A random starting point is selected and then every kth member of the population is selected for the sample. EXAMPLE A population consists of 845 employees of Nitra Industries. A sample of 52 employees is to be selected from that .