3.3 Graphics in the Media LEARNING GOAL Understand how to interpret the many types of more complex...

3.3Graphics in the Media

LEARNING GOAL

Understand how to interpret the many types of more complex graphics that are

commonly found in news media.

Copyright © 2009 Pearson Education, Inc.

Multiple Bar Graphs and Line Charts

A multiple bar graph is a simple extension of a regular bar graph: It has two or more sets of bars that allow comparison between two or more data sets.

All the data sets must have the same categories so that they can be displayed on the same graph.

Figure 3.18 A multiple bar graph. Source: Wall Street Journal Almanac.


A multiple line chart follows the same basic idea as a multiple bar chart, but shows the related data sets with lines rather than bars.

Figure 3.19 A multiple line chart. Source: New York Times.


Redraw this graph as a multiple line chart. Briefly discuss the trends shown on the graphs.

Figure 3.20 A multiple bar graph of trends in home computing. Source: Statistical Abstract of the United States.


Stack Plots

Another way to show two or more related data sets simultaneously is with a stack plot, which shows different data sets in a vertical stack.

Although data can be stacked in both bar charts and line charts, the latter are much more common.


Figure 3.22 shows death rates (deaths per 100,000 people) for four diseases since 1900. Based on this graph, what was the death rate for cardiovascular disease in 1980? Discuss the general trends visible on this graph.

Figure 3.22 A stack plot using stacked wedges. Sources: National Center for Health Statistics, American Cancer Society.


Geographical DataThe energy use data in Table 3.3 are an example of geographical data, because the raw data correspond to different geographical locations.

Figure 3.23 Geographical data can be displayed with a color-coded map.


TIME OUT TO THINK

What can you learn from the histogram in Figure 3.8 that you cannot learn easily from the geographical display in Figure 3.23? (Both are reproduced on the next slide.) What can you learn from the geographical display that you cannot learn from the histogram? Do you see any surprising geographical trends in Figure 3.23? Explain.


Figure 3.23 Geographical data can be displayed with a color-coded map.

For data that vary continuously across geographical areas, a contour map is more convenient.

Three-Dimensional Graphics

Combination Graphics

Figure 3.28 Women in the Olympics. Source: Adapted from the New York Times.Discuss 3 trends shown in Figure 3.28.Which of the trends do you think are likely to continue?

3.4 A Few Cautions About Graphics

LEARNING GOAL

Critically evaluate graphics and identify common ways in which graphics can be

misleading.

Perceptual Distortions

• The lengths of the bars represent the data but our eyes tend to focus on the area.

The heights of the TVs are the important measure but our eyes are drawn to the volume. Homes with Cable TV

18 million homes 73 million homes

Both graphs show the same data but they look very different because of the vertical scale.

Women as a Percentage of All College Students

Both graphs show the same data but the graph on the left has a vertical scale that is exponential.

Compare this graph with the graph on the next slide. This graph shows actual college costs and the next slide shows college costs as a percentage change.

Percentage change graph Notice the difference.

Pictographs • The art work may make the graph more appealing, but it can also distract or mislead.

• The line of people is purely decorative.

• The time intervals on the horizontal axis are not the same in each case.

3.3 Graphics in the Media LEARNING GOAL Understand how to interpret the many types of more complex...

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