Biology Reference
In-Depth Information
0.03
0.02
0.01
0
-0.01
-0.02
-0.03
-0.05
-0.04
-0.03
-0.02
-0.01
0
BGPC1
0.01
0.02
0.03
0.04
0.05
0.06
FIGURE 6.20
Scores of all 119 individuals projected onto BGPCs.
result of that computation for the 119 squirrel jaws is shown in
Figure 6.20
. It is important
to remember that this is the distribution of shapes in a subspace that was defined by the
positions of the means in a larger space. In the case of this example, the scores in the origi-
nal 26-dimensional space have been projected onto a two-dimensional plane. The PCs of
the original space accounted for only 42% of the variation; the plane of means likely
accounts for less than that. It is important to remember that all variation orthogonal to this
subspace has been excluded. It is only the differences between means that remain undis-
torted by this projection. The utility of examining scores of individuals on these axes will
depend on the scientific merits of focusing subsequent analyses on this subspace.
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