Worth 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.

• 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 cells:
  
  Figure title and caption in journal: Time course of lacZ expression in thymocytes from Substance Y-treated mice. Mice were injected with… (long caption deleted)
  
  Weak slide title (no message): LacZ expression
  
  Strong slide title (message): Substance Y mediates recombination in thymocytes
  
• 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.
  

Tips 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.
  
• Remember to place captions correctly: above tables and below figures. 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.