Graphics Reference
In-Depth Information
Figure
.
.
Classical scaling of virus data: Hord - Hordeviruses, Tobr - Tobraviruses, Toba -
Tobaviruses, Furo - Furoviruses
While the Sammon mapping produces a structure similar to that obtained using
classical scaling, the clusters are less clear cut. his differing view probably arises
because the mapping is an iterative procedure and is hence dependent on the initial
vector selected and the number of iterations performed.
Non-metric MDS
3.3
A non-metric approach to MDS was developed by Shepard (
a, b) and further
improved by Kruskal (
a, b). In summary, suppose there are n objects with dis-
similarities
. he procedure is to find a configuration of n points in a space,
which is usually chosen to be Euclidean, so that each object is represented by a point
δ
rs
