14. Statistical Techniques in Business & Economics (8)

8­ 1. Sa m p l i n g. Methods. &. Central Limit TheoremCopyright © 2004 by The McGraw­Hill Companies, Inc. All rights reserved. 8­ 2. When you have completed this chapter, you will be able to:. 1. Explain under what conditions sampling is the . proper way to learn something about a population 2. Describe methods for selecting a sample. . 3. Define and construct a sampling distribution . of the sample mean 4. Explain the central limit theorem 5. Use the central limit theorem to find probabilities of . selecting possible sample means from . a specified population. Copyright © 2004 by The McGraw­Hill Companies, Inc. All rights reserved. 8­ 3. We use sample information . We use sample information . to make . to make . decisions or inferences . decisions or inferences . about the population about the population Two KEY. Two KEY steps:. steps: 1. Choice of a proper method for selecting sample data. &. 2. Proper analysis of the sample data (more later) KEY 1 KEY 1Copyright © 2004 by The McGraw­Hill Companies, Inc. All rights reserved. 8­ © 2004 by The McGraw­Hill Companies, Inc. All rights reserved. 8­ 5. KEY 1 KEY 1 If the proper . method for selecting . the sample is . NOT MADE the SAMPLE . will not be truly . . representative of the . . TOTAL Population! . and wrong conclusions can be drawn!.Copyright © 2004 by The McGraw­Hill Companies, Inc. All rights reserved. 8­ 6 Why Sample the Population?. Why Sample the Population?. Because . of the physical impossibility of checking . all items in the population, and, . also, it would be too time­consuming. $ the studying of all the items in a population . would NOT be cost effective the sample results are usually adequate the destructive nature of certain testsCopyright © 2004 by The McGraw­Hill Companies, Inc. All rights reserved.