Information Technology Reference
In-Depth Information
Fig. 5.7
Zooming
in
to
reveal
a
detailed
structure
of
biomedicine
(Reproduced
from
Garfield 1998 )
Henry Small described what he called the synthesis of specialty narratives from
co-citation clusters (Small 1986 ). This paper won the JASIS best-paper award in
1986. Small first chose a citation frequency threshold to select the most cited
documents in SCI. The second step was to determine the frequency of co-citation
between all pairs of cited documents above the threshold. Co-citation counts
were normalized by Salton's cosine formula. Documents were clustered using the
single-link clustering method, which was believed to be more suitable than the
complete-link clustering algorithm because the number of co-citation links can be
as many as tens of thousands. Single-link clusters tend to form a mixture of densely
and weakly linked regions in contrast to more densely packed and narrowly focused
complete-link clusters. MDS was used to configure the layout of a global map.
Further, Small investigated how to blaze trails in the knowledge space represented
by the global map. He called this type of trail the specialty narrative .
Small addressed how to transform a co-citation network into a flow of ideas. The
goal for specialty narrative construction is to find a path through such networks so as
to track the trajectory of scientists who had encountered these ideas. Recall that the
traveling salesman problem (TSP) requires the salesman to visit each city exactly
once along a route optimized against a given criterion. We are in a similar situation
with the specialty narrative construction, or more precisely, the re-construction of
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