Analytical Writing for Science and Technology
Copyright © 1996 by T. M. Georges.

Lesson 19

Enhance Your Message with Illustrations and Tables


In this Lesson:

In this chapter, you'll learn how important your illustrations and tables are in getting your ideas across, and how to make them clear, informative and to-the-point. However, I won't cover details of actually preparing illustrations, such as how to draw graphs and which kinds of charts are best for which information. There are lots of books to help you do that. One is Writing and Speaking in the Technology Professions, edited by David Beer (IEEE Press, 1992).

The same analytical principles we've applied to writing apply to your illustrations as well. Be sure you have a clear and practical reason for including each figure and table, and that you're not just throwing something in because you have it lying around. Ask what purpose you want it to serve, and how you want your reader to respond to it. What questions might it raise? Are you presenting information that is easier to understand pictorially than in words? Answer these questions before you begin preparing your drawings, and you will stand a better chance of tuning your illustrations to your readers' needs.


Many business and technical writers think of illustrations, tables and their captions as afterthoughts -- something you have to clean up after you've finished the writing, but not really anything to pay much attention to. Consequently, illustrations often end up looking sloppy, unprofessional, and cluttered.

Look through any business or technical report that has illustrations and you can usually see what's wrong. If the report has charts or graphs, they are often not even labeled with enough information to let you figure out what they mean. Often, illustrations get tacked onto the end of a report, with their captions listed somewhere else. How often do you see an interesting picture but can't find the caption explaining it?

Now ask how important illustrations are to your reader. Usually they're the first thing that attracts his attention in an article or report. Pictures are inherently more interesting than words, even if they're graphs of dull business statistics. Every illustration has the potential for informing quickly, that is, if the information isn't buried.

When you pick up a document, don't you flip through it and stop at the illustrations? How do you process the information in them? How long do you spend trying to figure out what the pictures mean before you move on? If you see a clear, informative figure, isn't that often the only thing you remember about a paper?


If illustrations get so much attention, why are they so neglected? Why do most writers fail to take advantage of one of the most powerful tools for getting a point across quickly? Most often, they're simply not thinking about their readers' point of view. They're thinking about what they want to say, not what their readers are looking for.

Even when writers do prepare their illustrations carefully, they usually make them too complicated. They grossly overestimate their readers' ability to absorb complex data quickly. Often what happens is that you start out with a simple illustration that makes a single point, then you think of a dozen more things you can add in the same space. It's easy for you to understand because the concepts are familiar, and you've approached it in a step-by-step fashion. But someone seeing the whole collage for the first time is bound to be overwhelmed.

The most important thing to remember about your illustrations is: keep them simple and let each one make only a single point.

If you have more than one main point to make, use separate figures for each.


Captions are a grossly neglected part of most papers and reports. In fact, they are a grand opportunity to give you readers information at precisely the place and time they are looking for it. Many captions refer the reader to the text for further information. (Few readers accept that challenge -- do you?) Many are not even complete sentences. A typical caption might go like this:

Probability distribution of energy vs. distance from the earth (see text).


Sales for August (adjusted for returns).

Do you agree that such captions just raise more questions than they answer? Perhaps you think it's a good idea to withhold information in your captions, to entice your readers to read your paper. Does that really work? What is your response to uninformative captions? And how does your attitude toward a paper change if the figures are clear and you immediately find out what you're looking for in the captions? Write your comments here:

Here are some simple guidelines for writing informative figure captions:

1. Use complete sentences.

2. Try to make your illustrations as well as their captions self-sufficient, not depending on the text to be understood.

3. Explain the significance of all the information shown in the figure. If necessary, repeat and summarize some of the information from the text in the caption.

The captions in Scientific American are beautiful examples of self-sufficiency. You can always get a good idea of what each paper is about just by looking at its illustrations and reading their captions. Scientific American's captions are much longer than those of most papers in technical journals and business reports, because they contain much more information.

Here are a couple of exercises to give you practice writing informative captions.

Write an informative caption for this figure using the information and guidelines above. It is from a National Science Foundation report and shows how federal research funding is divided among scientific disciplines.

Here's another figure from the same NSF report. It shows public levels of confidence in various institutions. Write an informative caption for this figure.


Tables are notoriously dull and boring. No one likes to extract information from a list of numbers. So if you're going to present your information in the form of a table, make sure it's the best way to do it, and you'd better make it interesting.

Checklist for Informative Illustrations and Tables

Do you have a clear and practical reason for including this figure or table? What should your reader do about it?

Is the main point obvious at first glance? What is it?

Does each figure convey a single, well-defined message?

Are the captions complete sentences?

Does each caption explain the significance of the information in the figure?

Does each figure appear near the place in the text that refers to it, so that the reader doesn't have to flip pages?

If you're thinking of making a table with numbers in it, try to think of a way to present the information graphically instead. When people try to extract information from a table, they usually try to make sense out of it by making internal pictures of the relations between the numbers you give them. Why not save them the trouble and make the pictures for them? Then you'll be sure they focus on the relations you think are important, instead of the ones they happen to construct.

Simple illustrations like pie charts and bar graphs don't take any longer to prepare than a table, but are much easier to understand.

One kind of information that you can present better in a table than in any other form is detailed specifications that depend on two or more variables. One example is a matrix that shows the features of several new models of handheld calculators. If models are listed at the beginning of each row and the features listed at the head of each column, then a check mark in each "cell" shows at a glance which calculators have a desired feature, or which features a given calculator has. A potential buyer can compare features at a glance, instead of wasting his time flipping through separate lists of specifications.

More detailed information can be put in each cell, for example, if you want to describe the specifications of a number of radar installations. You could list each installation at the beginning of each line and tabulate things like frequency, beamwidth, modulation, range, and antenna type at the head of each column. In each cell there's room to put a brief description or specification, so that the reader can easily select or compare the specifications he's interested in.

Other kinds of tables tend to look like the phone book. Few readers will bother to extract the information you've buried in them unless you make it easy for them to zero in on exactly what they're looking for. Avoid tables, if you can.

Look at the figures and tables that illustrate a paper or report you have written. Apply the tests from the checklist above, answer all the questions, and note any improvements you could make.


Because your readers spend a relatively large amount of time on your illustrations, you should put a proportionately large amount of work into preparing them. Make sure they make a clear, unambiguous point and that their captions fully explain their significance. Avoid tables unless the form of your data demands it.

Next, I'll show you some practical ways to get started on your writing assignments. Once you get going, your momentum will often keep you going, but dealing with the mechanics of writing and overcoming "writers' block" and other forms of inertia can lock you in the starting gate.

-- End of Lesson 19 --

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