Information Technology Reference
In-Depth Information
TABLE 8.1 Total Number of Goals Scored by Teams 1
through 5 Ordered by Lowest Total to Highest Total
a
Team 4
Team 3
Team 1
Team 5
Team 2
11
14
16
18
22
a
These totals are for the Spring 2001 season. The
organization of the table correctly sorts on the numeric
variable. That the team labels are not sorted is far less
important since these labels are merely nominal; were it
not for the fact that we labeled with integers, the team
names would have no natural ordering.
ONE RULE FOR CORRECT USAGE OF
THREE-DIMENSIONAL GRAPHICS
As illustrated in the previous section, the introduction of superfluous
dimensions in graphics should be avoided. The prevalence of turnkey solu-
tions in software that implement these decorative presentations is alarm-
ing. At one time, these graphics were limited to business-oriented software
and presentations, but this is no longer true. Misleading illustrations are
starting to appear in scientific talks. This is partly due to the introduction
of business-oriented software in university service courses (demanded by
the served departments). Errors abound when increased license costs for
scientific- and business-oriented software lead departments to eliminate the
more scientifically oriented software packages.
The reader should not necessarily interpret these statements as a
mandate to avoid business-oriented software. Many of these maligned
packages are perfectly capable of producing scientific plots. Our warning is
that we must educate ourselves in the correct software specifications.
Three-dimensional perspective plots are very effective, but require speci-
fication of a viewpoint. Experiment with various viewpoints to highlight
the properties of interest. Mathematical functions lend themselves to
three-dimensional plots, but raw data are typically better illustrated with
contour plots. This is especially true for map data, such as surface temper-
atures, or surface wind (where arrows can denote direction and the length
of the arrow can denote the strength).
In Figures 8.8 and 8.9, we illustrate population density of children for
Harris County, Texas. Illustration of the data on a map is a natural
approach, and a contour plot reveals the pockets of dense and sparse pop-
ulations.
While the contour plot in Figure 8.8 lends itself to comparison of maps,
the perspective plot in Figure 8.9 is more difficult to interpret. The
surface is more clearly illustrated, but the surface itself prevents viewing all
of the data.
