Labelling:
In column headings, use parentheses to set the unit off from the description.
If your numbers are so big or so small that you need to use scientific
notation, try to put it in the headings, rather than attaching it to every
number in the table.
Layout: Align columns of numbers on decimal points. Left-justify columns of words.
Missing data: If you lack data in a table, include a place marker for the missing values. The marker should be consistent and its meaning (i.e., the reason for missing data) defined in a footnote to the table.
Organization: In presenting data in tables, use a consistent order, alphabetical if nothing else means more.
Keep the gaps between columns narrow, and keep the things that are most closely related closest together.
Set number comparisons vertically if possible. That layout also allows you to size the column widths appropriately for each column, instead of all being the same no matter how long or short the numbers are within them.
Referring to tables: Make sure the text says what people are supposed to get from the table. This will also help in electronic publication because people avoid loading tables.
Title:
Give a short descriptive title that distinguishes this table from all others
in the document. If there is more to be explained, give the explanation
after the short title. Put the table title above the table. The table title
should end in a period.
