Sample_Ch02

Sample_Ch02 - CHAPTER 2 Data Collection Chapter Contents...

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22 Data Collection Chapter Contents 2.1 Defnitions 2.2 Level oF Measurement 2.3 Time Series Versus Cross-Sectional Data 2.4 Sampling Concepts 2.5 Sampling Methods 2.6 Data Sources 2.7 Survey Research Chapter Learning Objectives When you fnish this chapter you should be able to Use basic terminology For describing data and samples. Explain the distinction between numerical and attribute data. Recognize levels oF measurement in data and ways oF coding data. Recognize a Likert scale and know how to use it. Explain the diFFerence between time series and cross-sectional data. Use the correct terminology For samples and populations. Explain the common sampling methods and how to implement them. ±ind everyday print or electronic data sources. Describe basic elements oF survey design, survey types, and sources oF error. CHAPTER 2
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23 In scientifc research, data arise From experiments whose results are recorded systemati- cally. In business, data usually arise From accounting transactions or management processes (e.g., inventory, sales, payroll). Much oF the data that statisticians analyze were recorded without explicit consideration oF their statistical uses, yet important decisions may depend on the data. How many pints oF type A blood will be required at Mt. Sinai Hospital next Thursday? How many dollars must State ±arm keep in its cash account to cover automotive accident claims next November? How many yellow three-quarter sleeve women’s sweaters will Lands’ End sell this month? To answer such questions, we usually look at historical data. 2.1 DEFINITIONS Data: Singular or Plural? Data is the plural oF the Latin datum (a “given” Fact). This traditional usage is preFerred in Britain, and especially in scientifc journals, where over 90 percent oF the reFerences use data as a plural (“These data show a correlation. ..”). But in the popular press (newspapers, magazines) you will oFten see “data” used synonymously with “inFormation” and hence as a singular (“The compressed data is stored on a CD. ..”). The singular usage is especially common in the United States and is becoming more common in the United Kingdom, rather to the chagrin oF the educated populace. Subjects, Variables, and Data Sets In this book, we will use data as a plural and data set when we reFer to a particular collection oF data as a whole. Each data value is an observation. A subject or individual is an item For study. An example oF a subject would be an employee in your company or an invoice statement generated last month. A variable is a characteristic oF the subject or individual. An example oF a variable might be the employee’s income. An observation oF that variable is the amount oF the employee’s income. Table 2.1 shows a small data set with eight subjects, fve variables, and 40 observations (eight subjects times fve variables).
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Attribute Data Attribute data (also called categorical, nominal, or qualitative ) have val- ues that are described by words rather than numbers. For example: Structural lumber type (e.g., X = fr, hemlock, pine).
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This note was uploaded on 09/23/2008 for the course ECON 13 taught by Professor Martin during the Spring '05 term at Tufts.

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Sample_Ch02 - CHAPTER 2 Data Collection Chapter Contents...

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