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Dr. Nees Jan van Eck
Centre for Science and Technology Studies (CWTS), Leiden University
Annual Research Directors’ Forum Meeting, CREST, Stellenbosch University
Stellenbosch, November 5, 2014
Multiple perspectives on bibliometric data
Bibliometric network analysis and science mapping using
VOSviewer and CitNetExplorer
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Centre for Science and Technology
Studies (CWTS)
• Research center of Leiden
University in quantitative
studies of science
(bibliometrics and
scientometrics)
• Bibliometric contract research
– Monitoring & evaluation
– Advanced analytics
– Training & education
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Short bio
• Master in computer science
• PhD thesis on bibliometric
mapping of science
• Since 2009, researcher at
Leiden University’s CWTS
– Bibliometric network analysis
– Bibliometric indicators of research
performance
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Bibliometric mapping of science
• Bibliometrics is the scientific field that
quantitatively studies all kinds of bibliographic data
• Bibliometric mapping of science is about
quantitative methods for visually representing
scientific literature based on bibliographic data
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Aim of bibliometric maps
• To provide an overview of the structure of the
scientific literature in a certain domain or on a
certain topic
• Applications:
– To identify the main research areas within a scientific field
– To get insight into the size of the different areas
– To see how the areas relate to each other
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Types of bibliometric maps
• Co-authorship maps of
– authors / organizations
• Co-citation maps of
– publications / journals / authors
• Bibliographic coupling maps
– publications / journals / authors / organizations
• Co-occurrence maps of
– keywords / terms extracted from titles and abstracts of articles
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Bibliographic databases
• Contain metadata about publications and their
citing publications
• Examples:
– Thomson Reuters’ Web of Science
– Elsevier’s Scopus
– MEDLINE
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– Authors
– Affiliations
– Source
– Volume
– Issue
– Pages
– Publications year
– DOI
– Title
– Abstract
– Keywords
– Document type
– Cited references
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Bibliometric networks
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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
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VOSviewer
• Web of Science support
• Natural language processing techniques
• State-of-the-art mapping and clustering algorithms
• Powerful visualizations
• Advanced zoom, scroll, and search functionality
• Smart label placement algorithm
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Bibliometric maps in VOSviewer
• Co-authorship maps of
– authors / organizations
• Co-citation maps of
– publications / journals / authors (first author only)
• Bibliographic coupling maps
– publications / journals / authors / organizations
• Co-occurrence maps of
– terms extracted from titles and abstracts of articles
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• 2,667 publications in 3 journals (time period 2009–
2013):
– Journal of Informetrics
– Journal of the American Society for Information Science and
Technology
– Scientometrics
• Data downloaded from the online version of Web of
Science
Demo: Creating different bibliometric
maps using VOSviewer
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Bibliographic coupling map of authors
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Co-citation map of journals
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Term map of social science research
on global environmental change
17Source: www.worldsocialscience.org/activities/world-social-science-report/the-2013-
report/read-changing-global-environments/
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Term map of clinical neurology
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Clinical Neurology: Citation density
19(Van Eck et al., PLoS ONE, 2012)
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Clinical Neurology: Reference density
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Structure of the computational
intelligence field 1996-2000
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Structure of the computational
intelligence field 1996-2000
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Structure of the computational
intelligence field 2001-2005
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Structure of the computational
intelligence field 2001-2005
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Evolution of the computational
intelligence field
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1996-2000 2001-2005
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Co-citation map of journals
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Journal application domains
27(Tijssen, JASIST, 2010)
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Co-authorship map of universities
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Source: www.leidenranking.com/methodology/additionalresources/
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Citation map of Web of Science fields
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Leiden University
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Erasmus University Rotterdam
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Delft University of Technology
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Large-scale mapping and clustering
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CitNetExplorer
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CitNetExplorer
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• Any type of bibliometric
network
• Co-citation and bibliographic
coupling of publications
• Time dimension is ignored
• At most about 10,000
publications are supported
• Only citation networks of
publications
• Direct citations between
publications
• Time dimension is explicitly
considered
• Millions of publications are
supported
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VOSviewer CitNetExplorer
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Why use CitNetExplorer?
• To analyze the structure and development of a
research field
– Example: Identifying the main topics in the field of
scientometrics and tracing the developments within each topic
• To delineate a research area
– Example: Delineating the literature on science mapping
• To study publication oeuvres
– Example: Identifying the publications of a researcher and
analyzing the influence of cited and citing publications
• To support literature reviewing
– Example: Reviewing the literature on the h-index
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• 26,002 publications in 14 journals (time period
1945–2013):
• Data downloaded from the online version of Web of
Science
Demo: Analyzing the structure and
development of scientometrics
American Documentation
ARIST
ASLIB Proceedings
Information Proc. & Manag.
Information Scientist
Information Storage & Retrieval
Journal of Documentation
Journal of Information Science
Journal of Informetrics
JASIS
JASIST
Research Evaluation
Research Policy
Scientometrics
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Structure of scientometric literature
• Citation analysis:
– Foundations
– Research evaluation
– Field normalization
– h-index
– Journal impact factor
• Science mapping
• Co-authorship and collaboration
• Scientometric laws
• Webometrics
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More
information
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Websites
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www.vosviewer.com www.citnetexplorer.nl
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Publications on VOSviewer
• Van Eck, N.J., & Waltman, L. (2010). Software survey: VOSviewer, a computer
program for bibliometric mapping. Scientometrics, 84(2), 523-538.
10.1007/s11192-009-0146-3
• Van Eck, N.J., & Waltman, L. (2009). How to normalize cooccurrence data? An
analysis of some well-known similarity measures. JASIST, 60(8), 1635-1651.
10.1002/asi.21075
• Waltman, L., Van Eck, N.J., & Noyons, E.C.M. (2010). A unified approach to
mapping and clustering of bibliometric networks. Journal of Informetrics,
4(4), 629-635. 10.1016/j.joi.2010.07.002
• Van Eck, N.J., Waltman, L., Dekker, R., & Van den Berg, J. (2010). A
comparison of two techniques for bibliometric mapping: Multidimensional
scaling and VOS. JASIST, 61(12), 2405-2416. 10.1002/asi.21421
• Waltman, L., & Van Eck, N.J. (2013). A smart local moving algorithm for large-
scale modularity-based community detection. European Physical Journal B,
86(11), 471. 10.1140/epjb/e2013-40829-0
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Publications on CitNetExplorer
• Van Eck, N.J., & Waltman, L. (2014). CitNetExplorer: A new software tool for
analyzing and visualizing citation networks. Journal of Informetrics, 8(4),
802-823. 10.1016/j.joi.2014.07.006
• Van Eck, N.J., & Waltman, L. (2014). Systematic retrieval of scientific literature
based on citation relations: Introducing the CitNetExplorer tool. In
Proceedings of the First Workshop on Bibliometric-enhanced Information
Retrieval (BIR 2014), pages 13-20. ceur-ws.org/Vol-1143/paper2.pdf
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Course: Bibliometric Network Analysis
and Science Mapping Using VOSviewer
• April 14-15, 2015
• Leiden University, The Netherlands
• Participants are introduced into the main
techniques for bibliometric network analysis and
science mapping
• Special attention is paid to applications in a
research evaluation and science policy context
• www.cwts.nl
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Thank you for your attention!
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