Section 2.1 Graphical Summaries for Qualitative Data 39 Pareto charts Sometimes it is desirable to construct a bar graph in which the categories are presented in order of frequency or relative frequency, with the largest frequency or relative frequency on the left and the smallest one on the right. Such a graph is called a Pareto chart. Pareto charts are useful when it is important to see clearly which are the most frequently occurring categories. EXAMPLE 2.4 Constructing a Pareto chart Construct a relative frequency Pareto chart for the data in Table 2.3. Solution Figure 2.2 presents the result. It is just like Figure 2.1(b) except that the bars are ordered from tallest to shortest. 0.5 0.4 0.3 0.2 0.1 0 Laptop Desktop Notebook Tablet Relative Frequency Figure 2.2 Pareto chart for the computer sales data Horizontal bars The bars in a bar graph may be either horizontal or vertical. Horizontal bars are sometimes more convenient when the categories have long names. EXAMPLE 2.5 Constructing bar graphs with horizontal bars The following relative frequency distribution categorizes employed U.S. residents by type of employment in the year 2009. Construct a relative frequency bar graph. Type of Employment Relative Frequency Farming, forestry, fishing 0.007 Manufacturing, extraction, transportation, and crafts 0.203 Managerial, professional, and technical 0.373 Sales and office 0.242 Other services 0.176 Source: CIA — The World Factbook Solution The bar graph follows. We use horizontal bars, because the category names are long. Employment of U.S. Residents 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Farming, forestry, fishing Manufacturing, extraction, transportation, and crafts Managerial, professional, and technical Sales and office Other services Relative Frequency Side-by-side bar graphs Sometimes we want to compare two bar graphs that have the same categories. The best way to do this is to construct both bar graphs on the same axes, putting bars that correspond to the same category next to each other. The result is called a side-by-side bar graph.
navidi_monk_essential_statistics_1e_ch1_3
To see the actual publication please follow the link above