Information Technology Reference
In-Depth Information
TABLE 8.4 Rank-Ordered List of Elementary Design
Choices for Conveying Numeric Information
a
Rank
Graphical Element
b
1
Positions along a common scale
2
Positions along identical, nonaligned scales
3
Lengths
4
Angles
4-10
Slopes
6
Areas
7
Volumes
8
Densities
9
Color saturations
10
Color hues
a
Slopes are given a wide range of ranks since they can be
very poor choices when the aspect ratio of the plot does
not allow distinction of slopes. Areas and volumes
introduce false dimensions to the display that prevent
readers from effective interpretation of the underlying
information.
b
Graphical elements are ordered from most (1) to least
(10) effective.
mation was measured for each style, and an ordered list of effective elemen-
tary design choices was inferred. The ordered list for illustrating numeric
information is presented in Table 8.4. The goal of the list is to allow the
reader to effectively differentiate among several values.
CHOOSING GRAPHICAL DISPLAYS
When relying completely on the ability of software to produce scientific
displays, many authors are limited by their mastery of the software. Most
software packages will allow users to either (a) specify in advance the
desired properties of the graph or (b) edit the graph to change individual
items in the graph. Our ability to follow the guidelines outlined in this
chapter is directly related to the time we spend learning to use the more
advanced graphics features of software.
SUMMARY
•
Examine the data and results to determine the number of dimen-
sions in the information to be illustrated. Limit your graphic to
that many dimensions.
•
Limit the axes to exactly (or closely) match the range of data in
the presentation.
•
Do not connect points in a scatterplot unless there is an underly-
ing interpolation that makes scientific sense.
