Rules for Using Tables and Figures
Tables and figures have a long been an important part of scientific communication. A look back at famous scientific manuscripts throughout the centuries will turn up all sorts of interesting drawings, diagrams, and map, and of course today, tables and figure will appear in the results section of almost every published research paper in the sciences. But just because we all use them doesn't mean that they're easy to produce. Indeed, creating a helpful, easy-to-read graphic for a research paper can be one of the more difficult tasks in the writing process.
Why use tables and figures?
Organizing lots of data in a way that makes sense is always a difficult task, and this task is particularly important in research papers. The reader needs to be able to quickly and easily digest the results of your work in order to move on to the next section. And, when it comes to organizing data, there's no better choice than tables and figures. When done correctly, these graphics will turn dense paragraphs of numbers into visual aids that help the reader identify important data and trends without a lot of hard work.
Note: Figures includes a wide range of graphics, including graphs, charts, maps, illustrations, and photographs. In this article we'll be focusing on the figures that are used to present data in the results section of a research paper.
Text, table, or figure?
The first question you need to ask yourself when you're looking at a big pile of data is whether it should be listed in the text, put into a table, or turned into a figure. Usually that's a decision that's up to your discretion, but there a few good guidelines to follow.
Text
It can be tempting to put all your data into tables and figures, but in fact there's nothing wrong with putting numbers directly in the main text as long as the results are simple and can be stated in a single sentence. A general rule is that if there isn't enough data to fill out a 3 x 3 table, then those values can just be listed in the text. For example, you might say "The number of participants who cited family issues as a source of anxiety was significantly higher in the treatment group (43%) than in the control group (65%, p < .05)." Your paper will be easier to read and less cluttered if you swap out small tables for a few simple sentences.
Tables
Tables should be used for listing large amounts of data by category. Each value in the table should stand on its own, meaning the reader should be able to look at a particular row and a particular column to find a unique result that doesn't need information other than what's in the table to be interpreted or explained. For example, if you have data that described a number of response variables (i.e., mean or percentage) from a set of questionnaires, that would go in a table.
Figures
Figures, on the other hand, are perfect when you need to show the relationship between sets of values. That data given in figures are important when compared with other values. Usually on a graph or chart, the reader won't be looking for a single numeric value like they would in a table; instead, figures should be designed so that readers can quickly understand how a series of number values relate to each other. So, if you have data from a set of questionnaires taken over a period of time and you wanted to visually show the changes from year to year, that job would best be done with a figure.
Four rules for tables and figures
#1: Table and figures should be focused
Many journals limit tables and figures because they take up a lot of space, but even if you're not being limited by a publisher, it's a good idea to use the minimum number of graphics needed to get the job done. Readers will be distracted or overwhelmed by papers that include too many tables, charts, or graphs, and they'll be likely to miss something significant. It's part of your job as the author is to decide what information is important enough to be included, which means you need to use your allotted tables and figures wisely.
When deciding which figures to use, start by identifying the storyline of your work and the key ideas that the reader needs to take away from the results section. Next, group together the data that address those individual messages and determine the best format for its presentation (e.g., table, bar graph, line graph, etc.). Lastly, design the graphics so that they stress the message you want readers to take away from your results (this doesn't mean leave out or manipulate data; it just means you should be aware of the key points you want the reader to see). Any table or figure that doesn't contribute significantly to the main storyline of your paper should be gotten rid of or merged with another graphic.
#2: Tables and figures should be simple
The best tables and figures will convey a lot of information using a small amount of space and a simple, easy-to-understand design. For tables, this means creating column and row headings that are clear and allow the reader to find information quickly. Also remember that only a single value should be included in each cell; grouping together lots of data will only clutter the table and confuse the reader.
It's especially important to focus on simplicity when it comes to figures like graphs and charts. It can be tempting to dress up a graph with fancy effects like shadows, loud colors, 3D effects, or gradients, but the more stuff you pile on an illustration, the harder it will be for the reader to interpret. Instead, choose one or two effects to highlight the message of the figure (for example, you can use differently shaped markers for data points on a graph), and get rid of anything that's merely decorative. Remember, this is a scientific paper, not a website or flyer: you want the picture to be functional, not pretty.
#3: Tables and figures should be designed for the reader
Keep in mind that most people read left to right and top to bottom, meaning readers are going to tackle tables and figures the same way, so organize your graphics so that they can be understand by readers using this natural progression. If a reader has to turn the paper or scan back and forth between sections, they might just skip that particular graphic.
Also (and this sounds very basic, but it needs to be said), tables and figures need to be readable. That means, simply, that your audience needs to be able to actually read the text. Data values, labels, and titles should all be large enough to be legible and should in an easy-to-read font (usually this means a sans-serif font like Arial or Helvetica). When working with figures, be careful not to place text over a textured background, like the gridlines for a graph, or over a darkened background, since both can make reading difficult.
#4: Tables and figures should stand alone
Readers shouldn't need to look back to the main text of your paper to understand and interpret tables and figures. That means that all the necessary information, including sample size, error values, and units, should be included somewhere on the graphic. You should also work on shaping short but informative titles for all the bits and pieces (e.g., column and row headings, lines and bars, axes) as well as for the tables and figures themselves. In addition, you should make use of captions and descriptions to fill in any other details the reader might need (e.g., locations, anomalies, or statistics summaries).
How much detail you put in the legends for tables and figures will depend on your professor or the style requirements for particular journals. Generally, if you have space for a thorough materials and methods section, then you won't need to go into too much detail in the results section. However, when trying to save space its often acceptable to keep the materials and methods section brief and include longer description in your figure and table legends.
In-text citations
Every table and figure included in the results section should be cited in the main body of the paper. These citations should always include a brief summary of the important points the reader will find in the graphic being referred to. You should never use a sentence to just direct the reader's attention to a table or figure-it's a waste of valuable space. For example, instead of saying "Figure 1 shows the increase in response levels over time," you would want to be more specific and say something like "Response levels rose 13% over the five-year period from 2000-2005 (Fig. 1)."
Tables and figures are two of your best weapons when it comes to presenting your research, so always make sure that yours are informative, focused, and easy to read.
