Information Technology Reference
In-Depth Information
T
ABLE
2.1.
Impact on performance (processing time and effectiveness) of
varying each of thethree parameters in turn,forboth data sets. Default param-
eter values are shown in parentheses. Note thatp
=
100,000 is not meaningful
for thedata set
SINGLE
.
Parameter
Data set
S
INGLE
M
ULTIPLE
CPU
Effective
CPUE fec ive
(msec)
(%)
(ms)
(%)
n
(
k
=10,
p
=100)
2
57.5
55.5
174.2
22.2
3
21.5
50.4
79.4
19.9
4
16.9
47.5
66.1
16.3
k
(
n
=2,
p
=100)
10
57.5
55.5
174.2
22.2
100
60.0
56.1
163.1
21.3
1000
111.3
55.9
228.8
21.4
p
(
n
=2,
k
=10)
100
57.5
55.5
174.2
22.2
1000
13.8
12.6
19.8
2.1
10,000
84.5
56.0
126.4
6.3
100,000
—
—
290.7
21.9
Fig. 11.14
Table with a deep hierarchy. There are two columns, one for parameters and one for data
sets. The latter is divided into two columns, one for each data set. Each data set has two columns of
figures. There are four rows, one of headings and one for each of the parameters
n
,
k
,and
p
. Each
of these is subdivided. Note that even this rather complex table does not require vertical rules. This
table might benefit from being separated into parts, but it is helpful to have all the data together.
There are insufficient data points for each combination of parameters to justify use of a graph
every row or column. (An example of this error is shown in Fig.
11.13
.) But do have
rules between groups of rows, and, in rare cases, between groups of columns, to act as
guides and to separate items that don't belong together. Don't make tables too dense.
Rather than cram in a large number of columns, have two tables, or, even better, be
selective about the information you present. In most tables no position should be
blank; if there is no applicable value, put in a dash, and explain somewhere what
it means. Values of the same units in a column should be aligned in a logical way.
Numbers should be aligned on the decimal point.
Using tables to show function values at different points is usually not a good idea
because graphs serve this purpose well; a possible exception is when a function only
has two or three values, in which case a graph would be too simple or sparse to be of
interest. If the table or graph shows only a simple relationship, consider stating the
relationship and omitting the diagram.
