Printed Page 306-334

Choosing the Appropriate Kind of Graphic

As Figure 12.7 shows, even a few simple facts can yield a number of different points. Your responsibility when creating a graphic is to determine what point you want to make and how best to make it. Don’t rely on your software to do your thinking; it can’t.

Graphics used in technical documents are classified as tables or figures. Tables are lists of data, usually numbers, arranged in columns. Figures are everything else: graphs, charts, diagrams, photographs, and the like. Typically, tables and figures are numbered separately: the first table in a document is Table 1; the first figure is Figure 1. In documents of more than one chapter (like this book), the graphics are usually numbered within each chapter. That is, Figure 3.2 is the second figure in Chapter 3.

The discussion that follows is based on the classification system in William Horton’s “Pictures Please—Presenting Information Visually,” in Techniques for Technical Communicators (Horton, 1992). Table 12.1 below presents an overview of the following discussion.

The kinds of graphics used most often to display numerical values are tables, bar graphs, infographics, line graphs, and pie charts.

Tables Tables convey large amounts of numerical data easily, and they are often the only way to present several variables for a number of items. For example, if you wanted to show how many people are employed in six industries in 10 states, a table would probably be most effective. Although tables lack the visual appeal of other kinds of graphics, they can handle much more information.

In addition to having a number (“Table 1”), tables are identified by an informative title that includes the items being compared and the basis (or bases) of comparison:

Table 3. Mallard Population in Rangeley, 2009–2011

Table 4.7. The Growth of the Robotics Industry in Japan and the United States, 2010

Each of these four graphs emphasizes a different point derived from the data in the table. Graph (a) focuses on the total number of railcars disabled each month, classified by cause; graph (b) focuses on the three rail lines during one month; and so forth. For information on bar graphs, see pages 312–17. For information on line graphs, see pages 319–22.

Figure 12.7 Different Graphics Emphasizing Different Points

Based on W. Horton, “The Almost Universal Language: Graphics for International Documentation” from TECHNICAL COMMUNICATION 40 (1993): 682–693.

Figure 12.8 illustrates the standard parts of a table.

Tables are usually titled at the top because readers scan them from top to bottom.

Some tables include a stub head. The stub—the left-hand column— lists the items for which data are displayed. Note that indentation in the stub helps show relationships. The heading “Natural Gas Liquids” is left-aligned. This row functions as a Totals row. Indented beneath this heading are the two categories that make up the totals: pentanes plus and liquefied petroleum gases. Beneath the heading are rows for the four kinds of liquefied petroleum gases.

Note that tables often contain one or more source statements and footnotes.

Note that tables often contain one or more source statements and footnotes.

Note that the numbers are right aligned.

Bar Graphs Like tables, bar graphs can communicate numerical values, but they are better at showing the relative values of two or more items. Figure 12.9 shows typical horizontal and vertical bar graphs that you can make easily using your spreadsheet software. Figure 12.10 shows an effective bar graph that uses grid lines.

Horizontal bars are best for showing quantities such as speed and distance. Vertical bars are best for showing quantities such as height, size, and amount. However, these distinctions are not ironclad; as long as the axes are clearly labeled, readers should have no trouble understanding the graph.

The five variations on the basic bar graph shown in Table 12.2 can help you accommodate different communication needs. You can make all these types using your spreadsheet software.

Infographics An infographic—short for information graphic—is a combination of words and graphics used to present factual data about a subject in a visually interesting way.

Designer Ivan Cash created this infographic by collecting data about infographics and then creating graphics to make the data interesting and visually appealing.

Infographics are built around basic types of graphical display: pie charts, line graphs, bar graphs, and diagrams. In an effective infographic, each visual display adheres to the conventions of the graphic on which it is based. For instance, in the “Countries Featured” bar graph, the length of each bar accurately reflects the quantity of the item it represents.

The art makes the data visually interesting, but the most important characteristic of an infographic is accuracy: the data must be accurate and presented fairly.

Figure 12.11, a portion of an infographic about infographics, shows many of the techniques used in this type of display.

Infographics are also an effective way to communicate information through a visual/verbal argument. Figure 12.12 shows a portion of an infographic that makes a very clear argument about the rising size of food portions.

Many organizations use infographics to present arguments. Here, the Centers for Disease Control compares fast-food portion sizes from the 1950s and today to make the case that, as the text at the top states, “Portion sizes have been growing. So have we.” The text goes on to suggest steps people can take to reduce their portion sizes.

Several sites on the web, such as infogr.am, offer free templates for making infographics.

Infographics are very popular, but many of them are of low quality. Before you create an infographic to communicate technical information, be sure you are not skewing your data or oversimplifying to promote an agenda. Doing so is unethical. In Figure 12.13, digital strategist Hervé Peitrequin offers a clever commentary on infographics.

Line Graphs Line graphs are used almost exclusively to show changes in quantity over time, for example, the month-by-month production figures for a product. A line graph focuses readers’ attention on the change in quantity, whereas a bar graph emphasizes the quantities themselves.

You can plot three or four lines on a line graph. If the lines intersect, use different colors or patterns to distinguish them. If the lines intersect too often, however, the graph will be unclear; in this case, draw separate graphs. Figure 12.14 shows a line graph.

Note that the title is lengthy because it specifically names the main variables presented in the graph. Name all the important data in the title; it is better for a title to be lengthy than to be imprecise or unclear.

The designer has included a caption that explains how to read the graph. Because this graph is illustrating several items that are measured in different units and therefore cannot be plotted on the same scale (including population and greenhouse gases), the designer chose to have the y-axis express variations from a norm. In this case, the norm is represented by the quantity of each item in the year 1990. If this graph illustrated several items that were measured in the same units, such as the sales figures, in dollars, of several salespersons, the designer would start the y-axis at zero.

Because the four data lines are sufficiently far apart, the designer placed the appropriate data label next to each line. Alternatively, the designer could have used a separate color-coded legend.

Each axis is labeled clearly.

Pie Charts The pie chart is a simple but limited design used for showing the relative sizes of the parts of a whole. You can make pie charts with your spreadsheet software. Figure 12.15 shows typical examples.

You can set your software so that the slices use different saturations of the same color. This approach makes the slices easy to distinguish from each other—without any distractions or misrepresentations caused by a rainbow of colors.

You can set your software to emphasize one slice by separating it from the rest of the pie.

Graphics can help you present logical relationships among items. For instance, in describing a piece of hardware, you might want to show its major components. The two kinds of graphics that best show logical relationships are diagrams and organization charts.

Diagrams A diagram is a visual metaphor that uses symbols to represent relationships among items or their properties. In technical communication, common kinds of diagrams are blueprints, wiring diagrams, and schematics. Figure 12.16 is a diagram.

The purpose of this diagram is to help people understand the different areas in their home that need to be insulated. In diagrams, items do not necesssarily look realistic. Here the designer is trying to represent logical relationships, not the physical appearances of items.

Organization Charts A popular form of diagram is the organization chart, in which simple geometric shapes, usually rectangles, suggest logical relationships, as shown in Figure 12.17. You can create organization charts with your word processor.

An organization chart is often used to show the hierarchy in an organization, with the most senior person in the organization in the box at the top.

Alternatively, an organization chart can show the functional divisions of a system, such as the human nervous system.

Graphics often accompany process descriptions and instructions (see Chapter 20). The following discussion looks at some of the graphics used in writing about actions: checklists, flowcharts, and logic trees. It also discusses techniques for showing motion in graphics.

Checklists In explaining how to carry out a task, you often need to show the reader what equipment or materials to gather, or describe an action or a series of actions to take. A checklist is a list of items, each preceded by a check box. If readers might be unfamiliar with the items you are listing, include drawings of the items, as shown in Figure 12.18. You can use the list function in your word processor to create checklists.

Often you need to indicate that readers are to carry out certain tasks at certain intervals. A table is a useful graphic for this kind of information, as shown in Figure 12.19.

Flowcharts A flowchart, as the name suggests, shows the various stages of a process or a procedure. Flowcharts are useful, too, for summarizing instructions. On a basic flowchart, stages are represented by labeled geometric shapes. Flowcharts can portray open systems (those that have a start and a finish) or closed systems (those that end where they began). Figure 12.20 shows an open-system flowchart and a closed-system flowchart. Figure 12.21 shows a deployment flowchart, which you can make using the drawing tools in your word processor.

Figure 12.20 Flowcharts

A deployment flowchart shows who is responsible for carrying out which tasks. Here the engineering staff writes the requisition, then sends it to the Engineering Manager.

Logic Trees Logic trees use a branching metaphor. The logic tree shown in Figure 12.22 helps students think through the process of registering for a course.

Techniques for Showing Action or Motion In some types of process descriptions and instructions, you will want to show action or motion. For instance, in an instruction manual for helicopter technicians, you might want to illustrate the process of removing an oil dipstick or tightening a bolt, or you might want to show a warning light flashing. Although animation and video are frequently used to illustrate action or motion in online documents, such processes still need to be communicated in static graphics for print documents.

If the reader is to perform the action, show the action from the reader’s point of view, as in Figure 12.23.

Figure 12.24 illustrates four additional techniques for showing action. These techniques are conventional but not universal. If you are addressing readers from another culture, consult a qualified person from that culture to make sure your symbols are clear and inoffensive.

To illustrate visual and spatial characteristics, use photographs, screen shots, line drawings, and maps.

Photographs Photographs are unmatched for reproducing visual detail. Sometimes, however, a photograph can provide too much information. In a sales brochure for an automobile, a glossy photograph of the dashboard might be very effective. But in an owner’s manual, if you want to show how to use the trip odometer, use a diagram that focuses on that one item.

Sometimes a photograph can provide too little information. The item you want to highlight might be located inside the mechanism or obscured by another component.

Screen Shots Screen shots—images of what appears on a computer monitor or some other screen—are often used in manuals to show users what the screen will look like as they perform tasks with the device. Readers who see that the screen shot accurately portrays what appears on their own devices are reassured and therefore better able to concentrate on the task they are trying to perform. Figure 12.26 is an example of how screen shots are used.

This screen shot, from a user guide on NASA’s website, shows users how to select a ringtone.

Line Drawings Line drawings are simplified visual representations of objects. Line drawings offer three possible advantages over photographs:

Figure 12.27 shows the effectiveness of line drawings.

This drawing, which accompanies a manual about the Americans with Disabilities Act, illustrates the idea that “wheelchair seating locations must provide lines of sight comparable to those provided to other spectators.” A photograph could not show this concept as clearly as this drawing does.

You have probably seen the three variations on the basic line drawing shown in Figure 12.28.

Maps Maps are readily available as clip art that can be modified with a graphics program. Figure 12.29 shows a map derived from clip art.

Include a scale and a legend if the map is one that is not thoroughly familiar to your readers. Also, use conventional colors, such as blue for water.