Information Technology Reference
In-Depth Information
−
4
4
−
2
4
−
2
0
0
2
2
6
6
15
4
15
4
6
6
8
8
8
8
10
10
12
PcExpD (1)
12
ParEdY (1)
10
16
PcExpD (1)
16
10
14
14
10
10
ParEdY (1)
10
10
16
8
16
8
EducY (0.99)
6
5
18
12
TScore (1)
EducY (0.99)
18
6
5
4
TScore (1)
4
2
0
2
0
Age (0.96)
Age (0.96)
Black; n
605
Coloured; n
=
Indian; n
=
19
4
=
90
White; n
=
85
−
2
4
0
0
2
2
6
15
15
4
6
4
6
6
8
8
8
8
10
10
12
12
PcExpD (1)
10
14
ParEdY (1)
16
16
14
PcExpD (1)
10
10
10
ParEdY (1)
16
10
8
10
16
EducY (0.99)
6
5
18
8
TScore (1)
12
18
EducY (0.99)
5
4
6
TScore (1)
2
0
4
Age (0.96)
Age (0.96)
Figure 4.24
CVA biplots of the 1993 education data. (Top left) Means
shown together with the individual samples obtained by calling
CVAbipl
with
specify.samples = 1:4
,
specify.bags = NULL
,
specify.ellipses = NULL
,
conf.alpha = NULL
. (Top right) 0.65-bags added to biplot obtained by call-
ing
CVAbipl
with
specify.classes = NULL
,
alpha = 0.65
,
specify.bags
= 1:4
,
specify.ellipses = NULL
,
conf.alpha = NULL
. (Bottom left) 0.65-el-
lipses added to biplot obtained by calling
CVAbipl
with
specify.classes
= NULL
,
specify.bags = NULL, specify.ellipses = 1:4
,
ellipse.alpha =
0.65
,
conf.alpha = NULL
. (Bottom right) 65% confidence ellipses added to biplot
obtained by calling
CVAbipl
with
specify.classes = NULL
,
specify.bags =
NULL
,
specify.ellipses = NULL
,
conf.alpha = 0.65
,
conf.type="both"
.
the black group and to a lesser degree for the coloured group but not for the other two
groups. This indicates a lack of homogeneity of within-groups covariance matrices. We
notice also that the given
α
-bags and
κ
-ellipses are almost identical for the coloured
and black groups but that they differ in the case of the two smaller groups. In the latter
case the nonparametric nature of the
α
-bag results in a figure that follows the data more
closely. Lastly, we add 65% confidence circles to the biplot as shown in the bottom
right panel. The outer circles about each mean do not contain the division by the factor
√
n
i
(see Section 4.2) and it is clear that as
n
i
increases the diameter of the inner circle
