Using figures and tables in a scientific manuscript
In preparing your manuscript, you may have information that you can present more efficiently in a figure or table. First, you need to decide which one is better. Tables are good for data that have a lot of variables or categories and if the values all follow the same pattern. Figures are useful for a reader to see comparisons between groups in columns or to show associations in regression plots. Sometimes, whether you choose one over the other will depend on space and how much data you have to present. Figures tend to summarize information visually, whereas tables allow space for more detail.
You should also avoid repeating information in your text and tables or figures. Journals do not want authors to give a list of numbers in the text and then give the same list in an accompanying table. Similarly, the information in a table does not also need to be visualized in a figure, and vice versa. If you create a table that is quite short, only two or three rows and columns, or a figure that is extremely simple, consider not using the table or figure and instead summarizing the information in a sentence or two in the text.
Regardless of how you choose to present your data, you’ll need to give the reader some context about what’s in the table or figure if you do use them. This context is called the “legend,” the short textual information that guides the reader in interpreting what they see.
What is a figure legend?
Figure legends tend to be longer than table legends. Usually, the first sentence or phrase is an overview of what is in the figure. An example is,
“Figure 1. Flowchart of patient selection.”
After that title, you can provide the reader with just enough background so that they can understand what they are seeing. For the complete legend, you might say:
“Figure 1. Flowchart of patient selection. Inclusion criteria were age over 18 and no history of asthma.Patients wereexcluded if they had asthma, were using an inhaler, or were taking oral steroids.”
Sometimes, a figure will have multiple parts, or panels. The usual approach is to label each of these with a letter: A, B, C, etc. Some journals use lowercase letters (a, b, c) and others use upper-case letters. You can learn which one your target journal uses by examining some of its recently published papers.
If you have panel labels, the letters and panels should all be incorporated into a single image file. They should not be added into a Word or other document file as extra images or text boxes on top of your existing figure image. In the legend, you will need to explain each panel that you label and give the reader a brief takeaway of what it shows. As an example, with a fictional figure with two panels, A and B:
“Figure 2. The effects of risolol before and after animals were fed. (A) Risolol effects before feeding. Animals showed nochanges in heart rate. (B) Risolol effects after feeding. Heart rate went up 10-fold, on average.”
Another way to present that information is as follows:
“Figure 2. The effects of risolol before (A) and after (B) animals were fed. Animals showed no changes inheart rate before feeding, but the rate increased 10-fold on average after feeding.”
The most important elements are telling the reader what the figure shows, overall (“Effects of risolol on heart rate” or a statement, “Risolol affects heart rate after feeding”), explaining what each panel shows, and giving a takeaway message about the findings. We also suggest that you place information such as P values in the figure legend rather than in the figure itself, to avoid cluttering up the image.
What is a table legend?
Table legends (also called “titles”) are quite different from figure legends. Usually, they consist only of a single phrase or sentence. For example:
“Table 1. Patient characteristics.”
If you need to offer more detail about what a table shows, the usual location for that information is in the table footnote, which is placed after the table. In the footnote, you can define terms that you abbreviate in the table, indicate the meaning of any superscript symbols you use (e.g., * to indicate P<0.05), and any other notes that help the reader understand what the table shows. These notes could include information about comparisons with different numbers of participants, or a methodological difference between comparisons in the table.
How figure and table legends differ?
In general, a figure legend will contain more detail and be placed as a single paragraph, either above or below the figure. When you submit a manuscript, journals usually ask authors to place all of their figure legends on a single page that follows the reference list, and then to upload the image files separately.
Table legends (also called “table titles”) will almost always be quite short and be placed above the table. Any detailed information is given below the table, in the footnote. For submission, tables usually are placed at the end of the manuscript following the figure legends page, with one table per page.
Some journals allow authors to put figures, tables, and legends near where they are mentioned in the text. You can consult journal guidelines, usually titled as “Instructions for authors,” “Author information,” “Journal guidelines,” or “Submission information,” to find out what your target journal wants.
Without exception, all figures and tables that you use in your manuscript must be cited in the text. In addition, you should number your figures and tables in the order of their appearance in the text.
How do you cite figures and tables in the text?
Journals vary in how they want these citations to look. Some journals use an abbreviation for figure (e.g., Fig. 1), but some do not (e.g., Figure 1). The use of panel labels in an in-text citation also varies (e.g., Fig. 1A, Figure 1A, Fig. 1(a), etc.). The best way to determine what the journal wants to see is to look at a recently published paper from your target journal for examples.
The word “table” is never abbreviated in the in-text citations. It is always given simply as “Table” (e.g., Table 1). In addition, almost all journals ask authors not to produce tables that have different parts (e.g., a, b, c). If you have a table that you’ve broken into, e.g., Table 1a and Table 1b, you will need to either merge it into a single Table 1 or split it into two tables, e.g., Table 1 and Table 2.
Sometimes, you will have supplementary material that has tables and figures. Journals vary in how they want supplementary elements cited in the text. Examples include Figure S1, Supplementary figure 1, Supplementary Fig. 1, Table S1, or Supplementary table 1. All elements that occur only in the supplementary material should be cited in the main text and numbered in their order of appearance.
