- Compare lengths of variables to show their relationships.
- Compare areas of variables to show their parts of a whole.
- Use actual figures in graphs when accuracy is needed.
Several researchers have studied design of tables aimed for the general public and other non-professional audiences. Generally speaking type size used in tables should be between 8 and 12 points. Readers prefer vertically oriented tables where it is easy to see the target entries, and then quickly find the data in the table cells to the right. It is easy to compare “side by side.” Horizontally oriented tables are harder to use and more difficult to understand. It is complicated to compare “up and down.” Tables may show the maximum amount of information in the minimum amount of space. However, tables are not always the best way to communicate numerical data. In friendly graphs, words are spelled out, they run from left to right (in western societies), and data are explained. Elaborately encoded shadings, cross-hatching, and colours are avoided. Colours are easy to distinguish, type is clear and precise, and is done in upper and lower case with serifs. In unfriendly graphs, abbreviations abound, words run in many directions. Graphics are repellent and cryptic with obscure coding. The design is insensitive to colour-deficient viewers Red and green are used for essential contrasts, and type is clotted and in all capitals in sans serif.
Numerical data and information can be presented in tables and in graphs. A table in an information material must have good readability. Therefore the information designer should:
- Provide all the information the learner will need in the table.
- Group items in a clear way.
- Put target entries to the left of the answers.
Wright and Fox1 made recommendations regarding design of tables in texts for the general public and other non-professional audiences. Some of the recommendations concern readability:
– All the information the learner will need should be presented in the table. That is, the learner should not be required to interpolate, combine entries, draw inferences, or otherwise manipulate the contents of the table in order to determine the correct answer. Rather, the learner should only be required to scan the list to find the correct target entry.
– Items within columns should be grouped and separated from other groups by either white space or rules (lines) in order to facilitate reading without accidentally moving to another row. Groups should contain no more than five items.
– Redundant abbreviations of units should not be included within the table entries (although they should be included in the column or row headings).
– Whenever possible, columns should be arranged so that the target entries are to the left of the answers. Also Ehrenberg provides guidelines for the construction of tables for the general public and other non-professional audiences:
– Numbers should be rounded off to no more than two significant figures to facilitate learners’ making comparisons. Averages of rows and columns (as appropriate) should be given to facilitate learners’ making comparisons of individual cell entries to them.
– Put the most important comparisons into columns (rather than rows), as columns make for the easiest comparisons.
- Numbers in rows or columns should be arranged in some meaningful order whenever possible (e.g., increasing or decreasing).