Lines in Tables
Summary:
Use light gray horizontal lines in tables, or no lines. Avoid vertical lines.
Details
Edward Tufte, Envisioning Information, p. 55
Tables should not be set to look like nets with every number enclosed.
Compare the following 2x2 table layouts:
From top to bottom, this shows a continuum from lots of lines in a table to no lines.
The table with gray horizontal lines is substantially easier to read than the top table (the one with black horizontal and vertical lines).
For some tables, removing all the lines, both horizontal and vertical, may enhance readability.
The bottom table takes the additional step of using a lighter color for the labels and totals, focusing attention on the four numbers in the middle of the table. My opinion is that this is the easiest layout of this table to read.
Rational:
- The human brain uses shading/color to automatically distinguish between foreground and background information (The Functional Art, p. 113). Dark lines, and a greater number of lines, make it harder for our brains to distinguish the important information (data in the table) from extraneous visual information (gridlines).
- Tufte recommends maximizing the ratio of data to ink (The Visual Display of Quantitative Information, 2nd Ed., p. 93). In this case, the numbers in the table are data; grid lines and labels are non-data “ink.”