This is a checklist for tables so that you can follow the AMA style guide. This is based on information at Section 1 Preparing an Article for Publication, subsection visual presentation of data, 4.1 Tables. If you are fiercely interested in this topic, you should check it out from the source. I have included most but not all of the finer details included there.
1. Make primary comparisons horizontal rather than vertical.
During the planning and creation of a table, the author should show the primary comparisons horizontally across the table, which makes them easier to compare. Independent variables conventionally are displayed in the left-hand column (stub) and the dependent variables in the columns to the right. Note that the second table more easily allows the reader to compare the differences based on color, which in this example, is the primary variable of interest.
2. Limit the amount of information presented in a single table (use multiple tables if necessary).
For the sake of clarity, you want to limit the amount of information presented and use more than one tables if needed. In general, tables in print publications can, depending on the content, contain up to 9 or 10 columns of data (including the first column, or stub). Cells that contain words will be wider, thereby reducing the number of columns that will fit, so keep that in mind.
3. Indent stubs to depict hierarchy.
Stubs (the left most column) should be left-justified, and indentions are used to depict hierarchical components of the stubs. However, some publications use bold stubs or shading instead.
4. Line up data with the first line in the stub entry.
5. Use a suitable title with a correct format.
If a manuscript contains only 1 table, it is referred to in the text as “Table.” If more than one table, you would number it 1, 2, etc. Table titles should use title case (words 4 or more letters capitalized). The title should convey the topic of the table succinctly but should not provide detailed background information or summarize or interpret the results.
Table. Bead Characteristics According to Color
6. Shorten column titles and expand abbreviations in a footnote if needed.
In column headings, style guidelines regarding numbers and abbreviations may be relaxed somewhat to save space, with abbreviations expanded in a footnote. However, when space allows spelled-out headings, expansions are preferable to abbreviations. Superscripted letters a-z should be used sequentially based on the order of placement in the table of the item to which the footnote refers. You can take a look at this table as an example. The placement of the footnote is tied to what is included in the reference. For example, in this table, the letter “i” is at the end of the subsection header, because the detail in the footnote refers to that entire section.
7. Use correct units of
In tables, units of measure, including the variability of the measurement if reported, should follow a comma in the table column heading or stub. The following are examples of stub entries with units of measure:
mean (SD), y
Systolic blood pressure, mean (SD), mm Hg
Body mass index, median (IQR)
Duration of hypertension, mean (SD) [range], y
Change in rate, % (SE)
8. Modify punctuation as needed (either for space or clarity).
Punctuation may abbreviated in tables to save space. For example, slashes may be used to present dates (eg, 1/24/19 instead of January 24, 2019) and hyphens may be used to present ranges (eg, 50–100 for 50 to 100). Phrases and sentences in tables may use end punctuation if required for readability (eg, if cells contain multisentence entries).
9. Use abbreviations properly.
Abbreviations can be used for space or clarity, however, spelled-out words should not be combined with abbreviations for units of measure. For example you should not use First y. Instead you would use “First Year” or “1st y” or “Year 1”. Abbreviations or acronyms should be explained in a footnote.
10. Present numbers accurately.
It’s possible to go into detail here, but the AMA Manual includes a lengthy discussion of how to present numbers accurately in any kind of medical writing, not just tables, and these same rules apply. For example, additional digits (including zeros) should not be added after the decimal point, to provide all data entries with the same number of digits. Doing so may indicate more precise results than actually were calculated or measured. In most cases, P values should be expressed to 2 digits to the right of the decimal point, unless the first 2 digits are zeros, in which case 3 digits to the right of the decimal place should be provided (eg, P = .002).