Tables can be a very important part of scientific papers.  A good scientific table should present the data simply, clearly and neatly, and allow the reader to understand the results without having to look at other sections of the paper.  However, a badly presented table could be very confusing, and may reduce the chances of your paper being accepted.  In this post, we will look at the basic rules of creating effective scientific tables.  Let’s begin with an example of a bad table, highlighting some common errors and showing how the formatting and content of the table can be improved.  Can you see anything wrong with this table?

Let’s start with the table formatting and editing.

1. Use a separate cell for each value

Look at the results in Table 1 . You can see that the author has placed two columns of data in the same cell.  We often see tables with only one row and column, with the data arranged using the space bar, or the tab button (as shown in the top of Fig. 1).

If the table is adjusted (for example, if the table size or text size is changed) the table layout may be affected, causing the data to be misplaced (as shown in the bottom of Fig. 1).  Additionally, if there are empty cells, rows or columns, it can be difficult to know if data is missing from the table, and impossible to know which columns the data should be in.

Tables should be created with the correct number of rows and columns.  You can also add new rows and columns to an existing table by right clicking on the table, selecting “Insert” and choosing to insert new rows and columns above or below the existing rows or columns.  It is also possible to insert multiple rows/columns to a table by highlighting the number of rows/columns you require on existing rows/columns.  For example, if you would like to add three columns to the left of your table, highlight the first three columns, right click and choose “Insert Columns to the Left”.

2. Use only horizontal line borders and double line spacing

Most journals ask that tables only contain only horizontal lines as borders.  Additionally, most journals require the tables in submitted manuscripts to be double spaced.  It is always a good idea to look at the “Instructions to Authors” for your journal, and check if there are any special instructions for the presentation of tables.

In Microsoft Word (version 2007 onwards), you can change the table borders by clicking on the table and using the menu which appears in the “Design” section under “Table Tools” as indicated by the red arrows in Fig. 2.  Alternatively, right click your mouse over the table, and click “Borders and Shading” to change the table borders.

Fig. 2: Changing the borders on a scientific table in Microsoft Word (version 2007 onwards).

Table line spacing can be changed in the same way as you would change the line spacing of normal text in a Word document. Don’t worry if the double spacing makes the table longer than one page.

Now the table is formatted correctly, let’s start to edit the scientific content.  Look back at Table 1 at the top of this page.  It is not very clear what the data in this table represents.  The table title is “Height after treatment”.  It could be the height of elephants, buildings or plants, and the title does not describe the treatment at all!  Always remember that each table must be understandable without other supporting text.  In other words, if the table was printed with only the title and footnotes, any another scientist should be able understand it, even if they work in a completely different area of research.  It can be very easy to forget to write the most important information when you are used to working with the same data for a long time!

3. Use clear and informative titles

Generally, you should include information on the test system (e.g. the species, cell line or type of patients), as well as the type of treatment (e.g. salinity or the drug name) and what was measured (e.g. plant height, blood pressure or cell proliferation).  So the title for the Table 1 could be:

Table 1.  Height of wheat plants after salinity treatment. -or-

Table 1.  Effect of salinity on the growth of wheat plants.

Sometimes, it can also be a good idea to describe the main result in the table title.  This will help the reader quickly understand your data.  For example:

Table 1.  Salinity reduces the growth of wheat plants. –or-

Table 1.  Exposure to salinity reduces the growth of wheat plants.

It’s not always possible or necessary to include the result in the table title, for example tables which show a list of data (such as patient characteristics, plant cultivars or PCR primers) or tables which contain complex or conflicting data.

Let’s see how the table changes if we apply these rules to the Table 1.  I’ll insert a new column to the left of the table and place each value in a separate cell (rule 1), only use vertical rules and double space the table (rule 2) and use an informative title (rule 3).

Do you think Table 1 is starting to look better yet?  There are still a large number of errors in Table 1!  Can you see any? In the second post in this series, I’ll discuss row and column titles, units, error values and sample sizes, and correct some more of the mistakes in Table 1.

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