applied in many topics, such as natural resource
management(Prell et al., 2009), classroom social
interactions(Martı
́
nez et al., 2003), economic
geography(Ter Wal & Boschma, 2009) and so on. In
the area of academic area, the social network of an
author or a researcher can be an indicator of his co-
authorship with other researchers. Liu et al. (2006)
examine the state of the digital library domain by
analyzing the co-authorship network of the past
ACM, IEEE, and joint ACM/IEEE digital library
conferences. At the same time, Newman learned the
pattern of scientific collaboration from a co-
authorship network (Newman, 2004). In addition,
Morel et al. (2009) found that co-authorship analysis
is a great tool to support the strategic planning of
research on neglected diseases.
2.2 Proposed Methods
In this project, the co-authorship network will be
analyzed by employing link analysis and graph
cluster analysis and a Spearman correlation test will
be conducted to learn the correlation between
academic performance and social network analysis
measures so that a productive researcher can be
identified. From the aspect of link analysis and
Spearman correlation test, the methods this paper will
employ refer to Abbasi et al.'s (2011,2012) in their
research. However, this paper extends their work by
applying the HITS algorithm (Kleinberg, 1998) to
identify the authority and hub of the network. In
addition, a graph cluster analysis based on two types
of betweenness algorithms will be employed. All of
these different analyses and algorithms help us to
make a better understanding of the microscopic of the
co-authorship network in China.
For link analysis, four measures of centrality will be
calculated. According to Freeman(1978), the
centrality of a node impacts leadership, satisfaction
and efficiency significantly. And the performance of
a node is impacted by betweenness centrality and
degree centrality particularly. The centrality
measures calculated in this project are degree
centrality, betweenness centrality, closeness
centrality and eigenvector centrality. The degree of a
node is the number of its adjacent nodes and it is
considered to be the measure of local centrality(Scott,
1991). Betweenness centrality(Borgatti,1995) is
another kind of centrality to measure the degree to
which a given node lies on the shortest paths
(geodesics) between other nodes in the graph.
Closeness(Freeman, 1980) is a measure of a node’s
global centrality by calculating its distance to other
nodes and eigenvector centrality(Bonacich, 1972) is
to measure a node’s centrality based on the concept
that the centrality of a node does not only depend on
the number of its adjacent nodes but also depend on
the centrality of these adjacent nodes.
Based on Burt’s s(Borgatti,1995) structural holes, this
paper also calculated the efficiency of nodes to
evaluate their relationship with authors in one group.
According to Burt, if a node has more primary
contacts from the same group, then the node will
obtain more redundant information from its primary
contacts as nodes within one group usually share the
same information. Therefore, a node’s network is
more efficient if it has a strong relationship with just
one node of a group rather than all authors within the
same group.
Additionally, this project employed Kleinberg’s
(1998) HITS algorithm to identify the authority and
hub of the network. A node is considered as an
authority if it has many pages linking to it and it is
considered as a hub if it points to many other vertices.
After link analysis, this project used two clustering
algorithms based on betweenness centrality to
conduct the graph cluster analysis. The result of the
two algorithms will be compared.
In order to learn how to identify the productive
researchers from their social network measures, the
significance of the relationship between four
centrality measures, efficiency and author's
performance will be evaluated by the Spearman
correlation test(Abbasi et al., 2011). Spearman
correlation test is a tool to evaluate whether two
variables are related to each other
significantly(Gauthier, 2001). The researchers'
performance in this project will be quantified by
using the g index, which was introduced by Egghe
(2006)and widely used by the academic database. The
g index is calculated by ranking a researcher's papers
in decreasing order of their papers’ number of
citations and the g index is the largest number that the
accumulated number of citations the top g papers
received is not less than g2.
The hypothesis tested by Spearman correlation
analysis are as below:
H1: A researcher’s degree centrality impacts his or
her research performance;
H2: A researcher’s betweenness centrality impacts
his or her research performance;
H3: A researcher’s closeness centrality impacts his or
her research performance;
H4: A researcher’s eigenvector centrality impacts his
or her research performance;
H5: A researcher’s efficiency impacts his or her
research performance;