Biology Reference
In-Depth Information
FIGURE 6.12
Graphical representation of the second step of
CVA. The new coordinate system (solid lines) is rescaled in pro-
portion to the pooled within-group variances in the original space.
Variation within samples will be circular in the new space if the
original variances were all identical. Note that the axes of the origi-
nal coordinate system (dotted) are not orthogonal in the new
space. Furthermore, distances in the new space are not equivalent
to distances in the original space (
Figure 6.10
).
X
2
X
1
PC1
FIGURE 6.13
Graphical
representation of the
final steps in CVA. (A) CV1
is the direction through
the rescaled space (outer,
dashed axes) in which the
group means are most dif-
ferent; CV2 is the direction
orthogonal to CV1 in which
the group means are most
different. (B) Scores of indi-
viduals in the CV space are
their projections onto the
CVs. Circles represent the
scores of one of the sample
means.
X
2
X
2
CV2
CV2
CV1
CV1
X
1
X
1
(A)
PC1
(B)
PC1
