Large-scale analysis of bibliometric
data sources
Nees Jan van Eck
Centre for Science and Technology Studies (CWTS), Leiden University
8th LCDS Meeting: Statistics & Data Science
Leiden, November 13, 2015

About myself
• Master in computer science
• PhD thesis on bibliometric
mapping of science
• Researcher at CWTS since 2009
• Research focus on analysis and
visualization of bibliometric
networks
1

Centre for Science and Technology
Studies (CWTS)
• Research center at Leiden University
focusing on science and technology
studies
• About 30 staff members
• History of more than 25 years in
bibliometric and scientometric
research
• Contract research
• Full access to large bibliographic
database (Web of Science and
Scopus)
2

Bibliographic databases: ‘Big data’
3
Web of Science Scopus
Journals 12,000 20,000
Publications 45 million 35 million
Citations 1 billion 0.9 billion

Bibliometric networks
4
Web of
Science
Scopus
Citation network
of publications
Co-authorship network
of authors / organizations
Co-citation network
of pubs / authors / journals
Co-occurrence network
of terms
Bibliographic coupling network
of pubs / authors / journals
Bibliographic
database

Outline
• Software tools
• Network analysis techniques
• Analysis of data science
5

Software tools
6

Software tools
• VOSviewer (www.vosviewer.com)
– Tool for constructing and visualizing bibliometric networks
• CitNetExplorer (www.citnetexplorer.nl)
– Tool for visualizing and analyzing citation networks of
publications
• Both tools have been developed together
with my colleague Ludo Waltman 7

VOSviewer
8

Map of university co-authorship
network
9

Map of journal citation network
10

CitNetExplorer
11

Network
analysis
techniques
13

Network analysis techniques
14
Layout:
• Visualization of similarities
(VOS)
Community detection:
• Weighted modularity
• Smart local moving algorithm

Smart local moving algorithm
15
Q = 0.4198
Q = 0.3791
Reduced
network
Local moving
heuristic in
subnetworks
Local moving heuristic
Original
network

Algorithmically constructed
classification system of science
• 16.2 million publications from the period 2000–
2014 indexed in Web of Science
• 241.7 million citation relations
• Classification system of 3 hierarchical levels:
– 28 broad disciplines
– 813 fields
– 3,822 subfields
16

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Breakdown of scientific literature into
813 fields
Social sciences
and humanities
Biomedical and
health sciences
Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering

Publications in scientometrics
subfield
18

Time-line map of highly cited
scientometrics publications
19

Analysis of
data science
20

What is data science?
• Empirical operationalization of data science based
on publications with ‘data’ in title or abstract
21
Wikipedia: “Data Science is an interdisciplinary field
about processes and systems to extract knowledge
or insights from data … which is a continuation of
some of the data analysis fields such as statistics,
data mining, and predictive analytics”
LCDS: “Data Science … deals with finding, analyzing
and validating complex patterns in data. Data
Science methods are indispensable for maintaining a
competitive edge in all disciplines in science”

Growth of data-driven research
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0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
1990 1995 2000 2005 2010 2015
Percentageofpublications
% 'data' publications % 'theory' publications

23
Breakdown of scientific literature into
813 fields
Social sciences
and humanities
Biomedical and
health sciences
Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering

24
Data-driven nature of different
scientific fields
Social sciences
and humanities
Biomedical and
health sciences
Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering
% pub. with ‘data’ in title or abstract

25
Data-driven nature of different
scientific fields
artificial
intelligence
statistics
bioinformatics
neuroimaging
pattern
recognition astronomy
earth
water
weather
climate
remote
sensing
nutrition
obesity
addiction
% pub. with ‘data’ in title or abstract

Data science fields (at least 20% ‘data’
publications)
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Social sciences
and humanities
Biomedical and
health sciences
Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering

Term map of data science fields
27

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Leiden University’s publication output
in data science fields
Social sciences
and humanities
Biomedical and
health sciences
Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering

Leiden University’s institutes with most
publications in data science fields
• Leiden Observatory
• LUMC
• Faculty of Archaeology
• Institute of Psychology (FSW)
• Centre for Science and Technology Studies (FSW)
• Mathematical Institute (Science)
• Institute of Biology Leiden (Science)
• Leiden Institute of Advanced Computer Science
(Science)
29

LUMC departments with most
publications in data science fields
• Medical Statistics and Bioinformatics
• Rheumatology
• Psychiatry
• Radiology
• Clinical Epidemiology
• Human Genetics
• Neurosurgery
• Cardiology
• Clinical Oncology
• Endocrinology 30

Term map based on Leiden University’s
publications in data science fields
31

Do it yourself!
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www.vosviewer.com www.citnetexplorer.nl

Thank you for your attention!
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