Table 2

Bibliometric statistics and network measures in three centers


DDRC
EMRC
PSRC
pvalue

Total papers
48
50
54
-
Total authors (size of network)
39
33
36
-
Papers per author (median(IQ range))
4(4)
4(4)
2(2.75)
P = 0.006
Maximum papers per author
42
43
22
-
Mean authors per paper
5(3)
4(2.2)
2.7(1.3)
p < 0.0001
Maximum authors per paper
12
11
6
-

Co-authorship network





Average co-authorship (median(IQ range))
23(35)
18(15)
6.5(7.5)
p < 0.0001
Collaborators per author (median(IQ range))
14(9)
10(7.5)
5(3)
p < 0.0001

Network centralization





Degree centralization
61.5%
63.8%
50.6%
-
Betweenness centralization
15.6%
27.7%
57.2%
-

Small world phenomenon





Average density
.417
.369
.151
-
Clustering coefficient
.729
.717
.735
-
Mean geodesic distance
1.6
1.6
2.3
-

Outsiders





Outsiders per author (median(IQ range))
21(26)
6(10)
5.5(5)
p < 0.0001
Spearman's correlation of inside and outside collaborations
0.8(p < 0.001)
0.49(p < 0.001)
0.32(p > 0.05)
-

Yousefi-Nooraie et al. Health Research Policy and Systems 2008 6:9   doi:10.1186/1478-4505-6-9