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Unformatted text preview: Chapter 2 The Graphical Representation of Data 2.1 The Histogram Today’s world has been described as the information age, and one of its peculiar characteristics is the abundance of data. Data in their raw form can be difficult to comprehend. One useful way to summarize a mass of data is by using graphical or pictorial representations. Many of these, pie charts, bar graphs, and so on, are easy to understand and commonly used. In this chapter, we will discuss the most important graphical representation in statistics, the histogram. To facilitate the understanding of how the histogram works, let’s invoke an example. The table below shows the percentage of families with incomes in each class interval per year in 000’s of Baht for Bangkok residents in some recent year. 1 2 CHAPTER 2. THE GRAPHICAL REPRESENTATION OF DATA Table 2.1: Annual income for a sample of Bangkok residence Income Baht ‘000 percent 0-30 1 30-60 3 60-90 6 90-120 10 120-150 11 150-210 24 210-270 20 270-390 18 390-600 5 over 600 1 To draw up the histogram, the first step would be put down the hor- izontal axis. The wrong way to do it is to have the same length for eachizontal axis....
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This note was uploaded on 03/14/2010 for the course ECON Statistics taught by Professor Yy during the Spring '10 term at Seoul National.
- Spring '10