a Thousand Words? How to Display Visual Data Effectively
Visuals are essential to scientific
publication and presentation. In the last paper you read—or presentation you viewed—wasn’t
nearly all of the evidence presented in the form of graphs, tables,
photographs, radiographs, or illustrations? Visuals show trends
and illustrate processes more clearly than text.
for visuals in oral presentations
Simplify your visual as much as possible. When presenting your data
on a slide, remember that the user is not a reader. The audience
cannot assimilate great detail and will probably have very little time
to process confusing data.
Avoid the lengthy titles and captions
used in written documents. Instead,
use informative message headings. The following is an example
from a figure that showed expression of the lacZ gene in mouse thymocytes,
which was evidence for recombination having occurred in the
Figure title and caption in journal: Time course of lacZ
expression in thymocytes from Substance Y-treated
mice. Mice were injected
Weak slide title (no message): LacZ expression
Strong slide title (message): Substance Y mediates recombination
Tag your image with labels or explanations. What needs definition?
What should the audience focus on? What is being compared?
Use arrows and text boxes to guide the audience to the most important features
of the visual.
Avoid large tables in oral presentations. If you must show a large
table, use color bars or faint rules (not dark lines) to
break up data.
Eliminate the legend in simple line
graphs and label the lines instead.
Your audience will not need to jump back and forth between
the legend and data to interpret the graph.
Use color effectively in bar and line
graphs. Avoid the overuse of
decorative color and the layering of two colors of similar
intensity (e.g., blue and red). Also, remember that about eight percent of
your male audience could be red-green color blind.
for visuals in written documents
Be cautious of colors when designing
graphs for publication. Your article
will invariably be downloaded and printed on black-and-white
printers or copied on black-and-white photocopiers. Therefore, even if the
journal will be printing your article (or the relevant page) in color,
avoid using color in bar and line graphs. If you choose to use color,
check to see that the chosen colors differ enough in grayscale to contrast
well when reproduced in black and white.
Keep your graphs, in general, as simple as possible. Graphs created
in 3D for purely aesthetic purposes are not as quickly interpreted
by your audience and may even be misleading. Be cautious of moiré effects
caused by busy fill patterns. Remove gridlines unless they
are absolutely essential to the argument.
Write an accurate, descriptive title and caption
for every figure. Many readers scan an article and view figures and
captions before reading
the article itself; here’s your chance to pique
interest and engage readers in your article.
to place captions correctly: above tables and below
Check reports and other documents that won’t
be copy edited.
To sum up, visuals allow you to show data more effectively
and tell the story of your research. When designing, remember to
consider specific needs of your audience. Graduate students are invited
to learn more at the Visual Display of Data Workshop, part of the
Leadership and Professional Development (LPD) series. To sign up,
go to http://www.owlnet.rice.edu/~cainproj/lpd/index.html.
|Mary Purugganan, PhD, works with the writing mentors
who support the biology courses.