148 Technical Writing: A Practical Guide for Engineers and Scientists
If there are too many graphical elements in a piece of writing, the reader
becomes distracted as the ow of the narrative is lost. If there are too few
graphical elements, the reader’s attention can also be lost in overly long tex-
tual passages. Many concepts can be illustrated via drawings, mathematics,
graphs, lists, and so forth. But how do you obtain the right mix of text and non-
text elements in technical writing? And how are these items best arranged?
7.2.1 A Picture Is Worth 1,437.4 Words
You have heard it said that a picture is worth a thousand words, but why not
1,437.4 words? Of course the cliché uses an arbitrary number because there
is no exact equivalence between a picture and ideas—but the point is that
pictures can be more effective and impactful than words alone in conveying
As an example, consider the following discussion of trafc fatalities for
In 1998 there were more than 1,170,000 reported trafc fatalities worldwide.
The number of trafc fatalities in poor nations was 8.7% higher than in
wealthy nations. China and Africa had the misfortune of leading the way
with more than 178,000 and 170,000 deaths, respectively. Of the wealthy
nations, those in Eastern Europe fared the best, with only 923 deaths.
This narrative only gives a tidbit of information about worldwide trafc
fatalities. To give a complete picture, I would have to go on with numbers
in textual form for many paragraphs. In addition to being hard to follow,
making the numbers interesting would be challenging without taking great
liberties of style that seem unwarranted.
Now consider Figure 7.1. This gure conveys more information and, I
contend, in a more compelling and easily digested way than the preceding
narrative description. The number of the fatalities per region, as depicted by
the boxes, grabs your attention and makes comparisons very easy.
But be aware that graphical representation can be used as a weapon to
shock the reader or misrepresent information to advance a hidden agenda. In
the case of Figure7.1, the whole story is not obvious because the chart gives
only gross fatalities, not fatalities as a percentage of population. India’s pop-
ulation in 1998 was estimated at 984,003,683, while China’s population was
1,236,914,658 during the same period (1998 CIA World Factbook). Computing
the number of trafc fatalities per 1,000 people in China and India, we get
0.01% versus 0.02%. India had twice the trafc fatality rate of China in that
year. Of course, there are deep underlying factors for this difference—dif-
ferences in mass transportation systems, roadways, population density, and
so forth that can be more easily described in words. Sometimes words are
better than pictures, although usually both together make the most powerful