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

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

1

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

2

Introduction

3

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

4

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

5

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

6

Bibliographic databases

• Contain metadata about publications and their

citing publications

• Examples:

– Thomson Reuters’ Web of Science

– Elsevier’s Scopus

– MEDLINE

7

– Authors

– Affiliations

– Source

– Volume

– Issue

– Pages

– Publications year

– DOI

– Title

– Abstract

– Keywords

– Document type

– Cited references

Bibliometric networks

8

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

VOSviewer

9

VOSviewer

10

11

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

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

12

• 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

13

Term map

14

Bibliographic coupling map of authors

15

Co-citation map of journals

16

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/

Term map of clinical neurology

18

Clinical Neurology: Citation density

19(Van Eck et al., PLoS ONE, 2012)

Clinical Neurology: Reference density

20

Structure of the computational

intelligence field 1996-2000

21

Structure of the computational

intelligence field 1996-2000

22

Structure of the computational

intelligence field 2001-2005

23

Structure of the computational

intelligence field 2001-2005

24

Evolution of the computational

intelligence field

25

1996-2000 2001-2005

Co-citation map of journals

26

Journal application domains

27(Tijssen, JASIST, 2010)

Co-authorship map of universities

28

Source: www.leidenranking.com/methodology/additionalresources/

Citation map of Web of Science fields

29

Leiden University

30

Erasmus University Rotterdam

31

Delft University of Technology

32

Large-scale mapping and clustering

33

CitNetExplorer

34

CitNetExplorer

35

• 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

36

VOSviewer CitNetExplorer

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

37

• 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

38

39

40

41

42

43

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

44

More

information

45

Websites

46

www.vosviewer.com www.citnetexplorer.nl

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

47

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

48

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

49

Thank you for your attention!

50