Information Technology Reference
In-Depth Information
TABLE 8.2 Volume of a Mixture Based on the Included
Fat and Surfactant Types
a
Fat
Surfactant
Volume
1
1
5.57
1
2
6.20
1
3
5.90
2
1
6.80
2
2
6.20
2
3
6.00
3
1
6.50
3
2
7.20
3
3
8.30
a
Problem:
The two categorical variables are equally of
interest, but the table uses only one direction for
displaying the values of the categories. This demonstrates
that table generation is similar to graphics generation, and
we should apply the same graphical rules honoring
dimensions to tables.
TABLE 8.3 Volume of a Mixture Based on the Included
Fat and Surfactant Types
a
Fat
Surfactant
1
2
3
1
5.57
6.20
5.90
2
6.80
6.20
6.00
3
6.50
7.20
8.30
a
The two categorical variables are equally of interest.
With two categorical variables, the correct approach is to
allow one to vary over rows and the other to vary over
columns. This presentation is much better than the
presentation of Table 8.2 and probably easier to interpret
than any graphical representation.
Specifying a
y
axis that starts at zero obscures the differences of the
results and violates Rule 3 seen previously. If we focus on the actual values
of the subgroups, we can more readily see the differences.
TWO RULES FOR TEXT ELEMENTS IN GRAPHICS
If a picture were worth a thousand words, then the graphics we produce
would considerably shorten our written reports. While attributing “a thou-
sand words” for each graphic is an exaggeration, it remains true that the
graphic is often much more efficient at communicating numeric informa-
tion than equivalent prose. This efficiency is in terms of the amount of
