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ENG302 : The Class : Rhetoric : Use of Graphics : Types of Graphics
Types of Graphics

Graphics in Technical Communication

Effective writing in business, industry, and government usually implies effective graphics. Technically oriented audiences often take a Missourian attitude-"Show me!" is the name of the game. Often the best way to show is by presenting data in the form of graphs, diagrams, flow charts, and other graphics. Basically, graphics refers to any of the document's nonprose elements, such as tables, charts, pictures, maps, etc. The writer has a twofold goal in creating graphics:

(1) to make the data stand out on the page and
(2) to make the data support the main purpose of the document as clearly and strongly as possible.
Effective graphics accomplish both these goals.


Many technical pieces of writing have two main kinds of material:
1) prose, the text or written part of the document and
2) supporting graphic material.
Generally speaking then, the text or prose contains directional material-ideas,of the document contains informational material-details that support the opinions and conclusions in the form of tables, charts, graphs, pictures, etc.

The text and the graphics support each other. Ideally, the reader grasps the writer's ideas and opinions from the text, and turns to the graphics for support of those ideas and opinions. The graphics in turn send the reader back to the text for more ideas. The reader moves back and forth down the page, first looking at text, and then at graphics. The reader clearly understands the main idea from the text and sees support for the main idea in the graphics. The writer organizes the document so that the facts in the graphics clearly support the main idea.

For this mutually supporting graphic and text relationship to work most effectively, the graphic must be visible simultaneously with the relevant text. The reader should not have to hunt around for a supporting graphic-it should jump out. Pagination, graphic size, and layout sometimes make it difficult to keep text and graphic together; however, the writer can usually achieve this important goal by planning ahead and being creative.

Conversely, the graphic must not be so detailed that the reader forgets the point of the text. Graphics are not ends in themselves. The text is primary-it contains the main point. Graphics must do their job and then get out of the way to let the text take over again.


This graphic and text relationship also implies that whenever possible, details should appear in graphic form. The reader should never have to plow through long and dense passages of prose that could appear as graphics instead.

Many different graphic formats can be used to support the text's main ideas. However, the ideal graphic format depends on the type of data being presented.

The table presents large amounts of data in a simple, brief, and clear linear format. The same data in prose would be bulky, confusing, and inaccessible. Tables help the reader grasp relationships that might be invisible in prose. Also, tables allow the writer to focus attention on specific pieces of data while retaining a clear presentation of the whole.

Graphs and Charts
Graphs and charts present numerical data pictorially, helping readers visualize relationships among those data.

Basically, the graph is a two-dimensional field used to plot the relationships among two interrelated sets of data. The most common sort of graph has the familiar X and Y axes, with data of one sort on the X axis and data of another related sort set on the Y axis. Such a representation allows the reader to see at a glance not just the data, but more important, the relationship between the two sets of data. For any value on either axis, the reader can quickly derive the related value or values on the other axis.

In creating graphs, the writer must select an appropriate scale for both axes. One too small distorts overall patterns, with even small variations appearing to cause large changes on the graph. One too large has the opposite effect, as even large variations in data will appear to have little impact on the basic shape of the graph.

While the graph illustrates relationships, the chart illustrates comparisons, usually among several sets of information.

Many other sorts of charts are possible, including the pie chart, the pictorial chart, which uses drawings to represent numerical information, and the map chart, a schematic representation of a geographical area, on which various pictures, drawings, or other devices are superimposed.

Photographs, Drawings, and Diagrams
When supporting material is pictorial rather than numerical, writers choose photographs, drawings, and diagrams as their graphic aids. All three use the same key principles:

1. All pictorial representations should conform to the general principles for any graphic aid:
Provide a detailed view of something difficult or impossible to convey in prose
Clearly support the text
Be visible simultaneously with the text they support

2. The details of the pictorial aid should be clear, especially those most relevant to the point being made. In a photograph,
clarity is achieved through good lighting, wisely chosen camera angle, and an absence of irrelevant background detail.
Drawings and diagrams use the same basic elements to achieve clarity: focus on relevant details and intelligent selection of
presentation angle.

3. Many pictorial graphic aids can be further clarified by superimposing explanatory labels to identify key parts. As always,
the writer's goal is to direct the reader's attention.

Photographs, drawings, and diagrams each have unique features. The writer considers these features when selecting which one of the three graphic aids to use.

Photographs are the most realistic and dramatic representation of physical features. In a good photograph the reader can see exactly what the writer is talking about. The range of photographic possibilities has greatly increased. Today's photographer has many special lenses that allow shots not possible before. Furthermore, cameras can be fastened to other equipment, such as microscopes and telescopes, to provide pictures not visible to the unaided human eye.

Finally, cameras can go places the human eye cannot normally go. For instance, photographs can be taken from a plane looking at the earth below or show magnified views of objects which would otherwise be indiscernible to the human eye.

Sometimes the writer wants to represent something that cannot be produced in the real world and so cannot be photographed. Other times a photograph is too expensive or time consuming. Then the writer uses a drawing. For instance, a cross section or cutaway view of a machine, while possible to photograph, requires ruining the machine-the only way to photograph a cross section of a coffee maker is to cut one in half!

Drawings may also be preferable to photographs when the writer wants to show things that cannot be photographed, such as a memory, or nonexistent or imaginary items, such as an artist's rendition of a proposed building.

Finally, sometimes writers want to show, not physical objects, but ideas. A diagram is a symbolic representation well-suited to the presentation of ideas. For instance, a flow diagram of a company's corporate structure symbolically represents the power relationships among employees. Another common diagram, based on a physical object, is the exploded view, which does not aim to picture the object, but to show the working relationships among its parts. Other typical examples of diagrams include blueprints, wiring schematics, and maps.

All these graphic aids have the common purpose of illustrating and supporting conclusions, recommendations, and interpretations the writer places in the text. The writer selects the exact graphic aid by considering the situation behind the writing-especially the purpose, audience, and author's role


The writer can incorporate some graphic devices into the prose itself. Such devices are designed to make the conclusions, opinions, and recommendations of the text jump out at the reader:

single-sentence paragraphs
headings and subheadings
numbering systems
boldface type
white space


The final draft of a business document usually contains two major parts:

Directional material, or text: The writer's own opinions, recommendations, and conclusions
Informational material, or graphics: The factual support for the writer's opinions

These two elements should be mutually supporting. The text leads the reader to the graphics; the graphics support the text. To accomplish this, graphics should always be visible simultaneously with the relevant text. The most useful graphic aids include the following:

• Tables
• Graphs
• Charts
• Photographs
• Drawings
• Diagrams

The writer should also use graphic effects to attract the reader's attention to the document's main and supporting points. The writer can use these options to make main points more highly visible.:

single-sentence paragraphs
headings and subheadings
numbering systems
boldface type
white space

Once you have finished reading this, you should:

Go on to Assignment 1: Construct a Table
Go back to the graphics topic page

E-mail Greg Larkin at Gregory.Larkin@nau.edu
or call (520) 523-4911

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