In August 2011, Thomson Reuters launched version 5 of the Science and Social
Science Citation Index in the Web of Science (WoS). Among other things, the 222
ISI Subject Categories (SCs) for these two databases in version 4 of WoS were
renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject
Categories (SCs) was added, but at a higher level of aggregation. Since we
previously used the ISI SCs as the baseline for a global map in Pajek (Rafols
et al., 2010) and brought this facility online (at
http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the
new WC categories using the Journal Citation Reports 2010. In the new
installation, the base maps can also be made using VOSviewer (Van Eck &
Waltman, 2010).Comment: Scientometrics, in pres

A Stirling

AL Porter

I Rafols

Ismael Rafols

J Melkers

L Leydesdorff

L Waltman

Loet Leydesdorff

NJ Eck Van

S Carley

S Soós

Stephen Carley

English

arXiv

[EN] In August 2011, Thomson Reuters launched version 5 of the Science and Social Science Citation Index in the Web of Science (WoS). Among other things, the 222 ISI Subject Categories (SCs) for these two databases in version 4 of WoS were renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but at a higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbreviated "SC'' in the download, whereas "WC'' is used for WoS Categories. Since we previously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freely available at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of the American Society for Information Science and Technology 61:1871-1887, 2010) and brought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the new WC categories using the Journal Citation Reports 2010. In the new installation, the base maps can also be made using VOSviewer (VOSviewer is freely available at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics 84:523-538, 2010).We acknowledge support from the ESRC grant RES-360-25-0076Leydesdorff, L.; Carley, S.; Rafols García, I. (2013). Global Maps of Science based on the new Web-of-Science Categories. Scientometrics. 94(2):589-593. https://doi.org/10.1007/s11192-012-0784-8589593942Carley, S., & Porter, A. L. (2012). A forward diversity index. Scientometrics, 90(2), 407–427.Leydesdorff, L., Hammarfelt, B., & Salah, A. A. A. (2011). The structure of the Arts & Humanities Citation Index: A mapping on the basis of aggregated citations among 1,157 journals. Journal of the American Society for Information Science and Technology, 62(12), 2414–2426.Leydesdorff, L., & Rafols, I. (2009). A global map of science based on the isi subject categories. Journal of the American Society for Information Science and Technology, 60(2), 348–362.Leydesdorff, L., & Rafols, I. (2011). How do emerging technologies conquer the world? An exploration of patterns of diffusion and network formation. Journal of the American Society for Information Science and Technology, 62(5), 846–860.Leydesdorff, L., & Rafols, I. (2012). Interactive overlays: A new method for generating global journal maps from web-of-science data. Journal of Informetrics, 6(3), 318–332.Melkers, J., & Hicks, D. (2012). Bibliometrics as a tool for research evaluation. In A. Link & N. Vornatas (Eds.), Handbook on the Theory and Practice of Program Evaluation. Cheltenham: Edward Elgar.Porter, A. L., & Rafols, I. (2009). Is science becoming more interdisciplinary? Measuring and mapping six research fields over time. Scientometrics, 81(3), 719–745.Porter, A. L., & Youtie, J. (2009). How interdisciplinary is nanotechnology? Journal of Nanoparticle Research, 11(5), 1023–1041.Rafols, I., & Leydesdorff, L. (2009). Content-based and algorithmic classifications of journals: Perspectives on the dynamics of scientific communication and indexer effects. Journal of the American Society for Information Science and Technology, 60(9), 1823–1835.Rafols, I., Leydesdorff, L., O’Hare, A., Nightingale, P., & Stirling, A. (2012). How journal rankings can suppress interdisciplinary research: A comparison between innovation studies and business & management. Research Policy, 41(7), 1262–1282.Rafols, I., Porter, A., & Leydesdorff, L. (2010). Science overlay maps: A new tool for research policy and library management. Journal of the American Society for Information Science and Technology, 61(9), 1871–1887.Soós, S., & Kampis, G. (2011). Towards a typology of research performance diversity: The case of top Hungarian players. Scientometrics, 87, 357–371.Stirling, A. (2007). A general framework for analysing diversity in science, technology and society. Journal of the Royal Society, Interface, 4(15), 707–719.Van Eck, N. J., & Waltman, L. (2010). Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics, 84(2), 523–538.Waltman, L., van Eck, N. J., & Noyons, E. (2010). A unified approach to mapping and clustering of bibliometric networks. Journal of Informetrics, 4(4), 629–635

Leydesdorff, L.

Carley, S.

Rafols García, Ismael

RiuNet

Global Maps of Science based on the new Web-of-Science Categories

Rafols, I.

Search4Dev

Global maps of science based on the new Web-of-Science categories

In August 2011, Thomson Reuters launched version 5 of the Science and Social Science Citation Index in the Web of Science (WoS). Among other things, the 222 ISI Subject Categories (SCs) for these two databases in version 4 of WoS were renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but at a higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbreviated "SC" in the download, whereas "WC" is used for WoS Categories. Since we previously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freely available at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of the American Society for Information Science and Technology 61:1871-1887, 2010) and brought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the new WC categories using the Journal Citation Reports 2010. In the new installation, the base maps can also be made using VOSviewer (VOSviewer is freely available at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics 84:523-538, 2010)

International Migration, Integration and Social Cohesion online publications

UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)UvA-DARE (Digital Academic Repository)Global maps of science based on the new Web-of-Science categoriesLeydesdorff, L.; Carley, S.; Rafols, I.DOI10.1007/s11192-012-0784-8Publication date2013Document VersionFinal published versionPublished inScientometricsLink to publicationCitation for published version (APA):Leydesdorff, L., Carley, S., & Rafols, I. (2013). Global maps of science based on the newWeb-of-Science categories. Scientometrics, 94(2), 589-593. https://doi.org/10.1007/s11192-012-0784-8General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an opencontent license (like Creative Commons).Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, pleaselet the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the materialinaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letterto: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. Youwill be contacted as soon as possible.Download date:11 Feb 2023Global maps of science based on the new Web-of-SciencecategoriesLoet Leydesdorff • Stephen Carley • Ismael RafolsReceived: 9 February 2012 / Published online: 17 June 2012 The Author(s) 2012. This article is published with open access at Springerlink.comAbstract In August 2011, Thomson Reuters launched version 5 of the Science and SocialScience Citation Index in the Web of Science (WoS). Among other things, the 222 ISISubject Categories (SCs) for these two databases in version 4 of WoS were renamed andextended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but ata higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbre-viated ‘‘SC’’ in the download, whereas ‘‘WC’’ is used for WoS Categories. Since wepreviously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freelyavailable at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of theAmerican Society for Information Science and Technology 61:1871–1887, 2010) andbrought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibratedthis map for the new WC categories using the Journal Citation Reports 2010. In the newinstallation, the base maps can also be made using VOSviewer (VOSviewer is freelyavailable at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics84:523–538, 2010).Keywords Map  Overlay  Web of Science  Subject categories  InterdisciplinarityL. Leydesdorff (&)Amsterdam School of Communication Research (ASCoR), University of Amsterdam,Kloveniersburgwal 48, 1012 CX Amsterdam, The Netherlandse-mail: loet@leydesdorff.netURL: http://www.leydesdorff.netS. CarleySchool of Public Policy, Georgia Tech, Atlanta, GA, USAe-mail: stephen.carley@gmail.comI. RafolsSPRU (Science and Technology Policy Research), University of Sussex,Freeman Centre, Falmer Brighton, East Sussex BN1 9QE, UKe-mail: i.rafols@sussex.ac.uk123Scientometrics (2013) 94:589–593DOI 10.1007/s11192-012-0784-8The WC categories are sometimes different from the old SCs. For example, the EuropeanJournal of Pharmaceutics and Biopharmaceutics, which was previously classified to theISI SC ‘‘Engineering, Chemical’’ was now assigned to ‘‘Pharmacology and Pharmacy.’’ Inan Annex, Rafols et al. (2010) showed that with aggregated sets the map is relatively robustagainst error in the classifications, but the differences can be significant at lower levels ofaggregation (Rafols and Leydesdorff 2009). As noted, the semantics may be confusing:WoS Subject Categories (WC) replace the old ISI Subject Categories (SC), but the oldlabel SC for Subject Categories is now used in the download for the 151 newly created‘‘Subject Areas’’ as they are called at the WoS interface. Both in the old and the newsituation there are additionally 25 Subject Categories which are used exclusively in theArts & Humanities Citation Index (A&HCI), and not included in our analysis becauseA&HCI does not have (hitherto) a Journal Citation Report (Leydesdorff et al. 2011, atpp. 2417 ff.). Table 1 summarizes the changes.Whereas previously 18 factors were found most appropriate for explaining the structureof the aggregated citation matrix, an organization into 19 factors explaining 54.3 % of thevariance is most apt for showing the disciplinary structure of the new matrix. The changesare mainly in the organization of mathematics. Rafols et al. (2010, at p. 1876) alreadynoted that ‘‘the position of mathematics (all math subject categories) in the map remainsopen to debate. Since different strands of mathematics are linked to different major fields(medicine, engineering, social sciences), these may show as diverse entities in distantpositions, rather than as a unitary corpus, depending on metrics, classifications, andclustering algorithms used.’’In the new overlays, the previous factor of ‘‘Computer Science’’ is divided into twogroups and designated (by us) as ‘‘Computer Science’’ and ‘‘Mathematical Methods.’’Table 2 provides the subject categories organized within these two compartments. Theother 17 factors could remain similar to the previous classification (Rafols et al. 2010).As with our previous installation, the base map with the relevant initialization routinefor Pajek (v. 2.05) is available on the internet. The new base map can also be used as inputto VOSviewer (Van Eck and Waltman 2010), but this did not improve the visualization inthe case of 19 clusters. (See for more discussion about the differences between the twovisualization techniques Leydesdorff and Rafols (2012).) However, the clustering algo-rithm in VOSviewer distinguished four, in our opinion highly meaningful, groupsTable 1 Changes in the organization of subject categories and subject areas between versions 4 and 5 of WoSWoS version 4 WoS version 5Subject categories (SCI ? SoSCI) 222 ISI subjectcategoriesa225 WoS subject categoriesAbbreviation in the download SC WCA&HCI 25 ISI subjectcategories26 WoS subject categoriesSubject areas \not defined[ 151 subject areas; abbreviated SCin the downloadOne of the 225 WC is no longer in use; this is: ‘‘Biology, Miscellaneous’’. Only a single journal (GrowthDevelopment and Aging) is attributed to this category. Although this journal was cited 520 times in 2010 andis listed with an IF-2010 = 3.000, it is not processed in the Journal Citation Reports (JCR) from the citingside. In summary, we use the matrix of 224 WCsa Three additional categories were no longer in use (Rafols and Leydesdorff 2009)590 L. Leydesdorff et al.123(Waltman et al. 2010). The organization into these four groups (biomedical, physical,environmental, and social sciences) is now provided as another (optional) partition withinthe Pajek (.paj) file containing the base map, and is also made available as input toVOSviewer.The routine allows the user to make an overlay choosing one of the following tworoutes:1. Within the WoS (v. 5.5), one can ‘‘Analyze Results’’ by clicking at the right top of thepage with search results; choose ‘‘Web of Science Categories’’ among the rankingoptions, and export the data into a file ‘‘analyze.txt’’. This file can be read by theprogram wc10.exe, and the resulting file ‘‘wc10.vec’’ can be imported into the basemap as a vector.1 The visualization (Draw-Partition-Vector within Pajek) then showsthe overlay (e.g., Fig. 1).2. The routine wc10.exe also generates three so-called ‘‘map’’-files for VOSviewer:vos4.csv, vos6.csv, and vos19.csv. (The csv-extension makes these text files alsoreadable using Excel.) These files generate maps when read into VOSviewer with four,six, and 19 clusters, respectively (using different colors). The manual of VOSviewercan be consulted for further options (Fig. 2).A PowerPoint file is provided at http://www.leydesdorff.net/overlaytoolkit/basemaps.pptx which allows the user to place the legends on top of the maps and which provides afew examples; these legends can also be edited. An additional routine enables the user tomeasure Rao-Stirling diversity as an index of the interdisciplinarity in the samples understudy (cf. Carley and Porter 2012; Leydesdorff and Rafols 2011; Porter and Rafols 2009;Rafols et al. 2012; Stirling 2007).By thus adjusting to the new situation, we hope to have provided the community with ameans to map inter- and multidisciplinary sets of documents in future research using thenew version of the Web of Science (cf. Leydesdorff and Rafols 2009; Melkers and HicksTable 2 Distinction between ‘‘computer science’’ and ‘‘mathematical methods’’ in terms of WoS subjectcategories12 WC attributed to ‘‘computer science’’ 6 WCs attributed to ‘‘mathematical methods’’Computer science, hardware and architecture Computer science, interdisciplinary applicationsEngineering, electrical and electronic Operations research and management scienceComputer science, artificial intelligence Mathematics, appliedComputer science, theory and methods Statistics and probabilityComputer science, information systems Engineering, industrialTelecommunications MathematicsAutomation and control systemsComputer science, cyberneticsComputer science, software engineeringRoboticsImaging science and photographic technologyTransportation science and technology1 The same file ‘‘wc10.vec’’ is automatically generated when using the routine ISI.exe for organizing thesaved output of the WoS, as specified at http://www.leydesdorff.net/software/isi.Global maps of science 5911232012; Porter and Youtie 2009; Soós and Kampis 2011). A detailed manual for the mappingwas provided (at the website) by Ken Riopelle. Additionally, a macro to transform the file‘‘analyze.txt’’ into the Gephi format was provided by Clement Levallois.Acknowledgments We are grateful to Alan Porter for comments on a previous draft. We acknowledgeThomson Reuters for the use of the data. We acknowledge support from the ESRC grant RES-360-25-0076.Fig. 1 Disciplinary composition of 5,793 citable items (articles, proceedings papers, and reviews)published in 2009 with an address at Oxford University; Rao-Stirling = 0.856. (Pajek used for thevisualization.)Fig. 2 Disciplinary composition of 5,468 citable items (articles, proceedings papers, and reviews)published in 2009 with an address at the University of Cambridge; Rao-Stirling = 0.851. (VOSviewer usedfor the visualization.)592 L. Leydesdorff et al.123Open Access This article is distributed under the terms of the Creative Commons Attribution Licensewhich permits any use, distribution, and reproduction in any medium, provided the original author(s) and thesource are credited.ReferencesCarley, S., & Porter, A. L. (2012). A forward diversity index. Scientometrics, 90(2), 407–427.Leydesdorff, L., Hammarfelt, B., & Salah, A. A. A. (2011). The structure of the Arts & Humanities CitationIndex: A mapping on the basis of aggregated citations among 1,157 journals. Journal of the AmericanSociety for Information Science and Technology, 62(12), 2414–2426.Leydesdorff, L., & Rafols, I. (2009). A global map of science based on the isi subject categories. Journal ofthe American Society for Information Science and Technology, 60(2), 348–362.Leydesdorff, L., & Rafols, I. (2011). How do emerging technologies conquer the world? An exploration ofpatterns of diffusion and network formation. Journal of the American Society for Information Scienceand Technology, 62(5), 846–860.Leydesdorff, L., & Rafols, I. (2012). Interactive overlays: A new method for generating global journal mapsfrom web-of-science data. Journal of Informetrics, 6(3), 318–332.Melkers, J., & Hicks, D. (2012). Bibliometrics as a tool for research evaluation. In A. Link & N. Vornatas(Eds.), Handbook on the Theory and Practice of Program Evaluation. Cheltenham: Edward Elgar.Porter, A. L., & Rafols, I. (2009). Is science becoming more interdisciplinary? Measuring and mapping sixresearch fields over time. Scientometrics, 81(3), 719–745.Porter, A. L., & Youtie, J. (2009). How interdisciplinary is nanotechnology? Journal of NanoparticleResearch, 11(5), 1023–1041.Rafols, I., & Leydesdorff, L. (2009). Content-based and algorithmic classifications of journals: Perspectiveson the dynamics of scientific communication and indexer effects. Journal of the American Society forInformation Science and Technology, 60(9), 1823–1835.Rafols, I., Leydesdorff, L., O’Hare, A., Nightingale, P., & Stirling, A. (2012). How journal rankings cansuppress interdisciplinary research: A comparison between innovation studies and business & man-agement. Research Policy, 41(7), 1262–1282.Rafols, I., Porter, A., & Leydesdorff, L. (2010). Science overlay maps: A new tool for research policy andlibrary management. Journal of the American Society for Information Science and Technology, 61(9),1871–1887.Soós, S., & Kampis, G. (2011). Towards a typology of research performance diversity: The case of topHungarian players. Scientometrics, 87, 357–371.Stirling, A. (2007). A general framework for analysing diversity in science, technology and society. Journalof the Royal Society, Interface, 4(15), 707–719.Van Eck, N. J., & Waltman, L. (2010). Software survey: VOSviewer, a computer program for bibliometricmapping. Scientometrics, 84(2), 523–538.Waltman, L., van Eck, N. J., & Noyons, E. (2010). A unified approach to mapping and clustering ofbibliometric networks. Journal of Informetrics, 4(4), 629–635.Global maps of science 593123

Springer - Publisher Connector

Global maps of science based on the new Web-of-Science
categories
Loet Leydesdorff • Stephen Carley • Ismael Rafols
Received: 9 February 2012 / Published online: 17 June 2012
 The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract In August 2011, Thomson Reuters launched version 5 of the Science and Social
Science Citation Index in the Web of Science (WoS). Among other things, the 222 ISI
Subject Categories (SCs) for these two databases in version 4 of WoS were renamed and
extended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but at
a higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbre-
viated ‘‘SC’’ in the download, whereas ‘‘WC’’ is used for WoS Categories. Since we
previously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freely
available at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of the
American Society for Information Science and Technology 61:1871–1887, 2010) and
brought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibrated
this map for the new WC categories using the Journal Citation Reports 2010. In the new
installation, the base maps can also be made using VOSviewer (VOSviewer is freely
available at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics
84:523–538, 2010).
Keywords Map  Overlay  Web of Science  Subject categories  Interdisciplinarity
L. Leydesdorff (&)
Amsterdam School of Communication Research (ASCoR), University of Amsterdam,
Kloveniersburgwal 48, 1012 CX Amsterdam, The Netherlands
e-mail: loet@leydesdorff.net
URL: http://www.leydesdorff.net
S. Carley
School of Public Policy, Georgia Tech, Atlanta, GA, USA
e-mail: stephen.carley@gmail.com
I. Rafols
SPRU (Science and Technology Policy Research), University of Sussex,
Freeman Centre, Falmer Brighton, East Sussex BN1 9QE, UK
e-mail: i.rafols@sussex.ac.uk
123
Scientometrics (2013) 94:589–593
DOI 10.1007/s11192-012-0784-8
The WC categories are sometimes different from the old SCs. For example, the European
Journal of Pharmaceutics and Biopharmaceutics, which was previously classified to the
ISI SC ‘‘Engineering, Chemical’’ was now assigned to ‘‘Pharmacology and Pharmacy.’’ In
an Annex, Rafols et al. (2010) showed that with aggregated sets the map is relatively robust
against error in the classifications, but the differences can be significant at lower levels of
aggregation (Rafols and Leydesdorff 2009). As noted, the semantics may be confusing:
WoS Subject Categories (WC) replace the old ISI Subject Categories (SC), but the old
label SC for Subject Categories is now used in the download for the 151 newly created
‘‘Subject Areas’’ as they are called at the WoS interface. Both in the old and the new
situation there are additionally 25 Subject Categories which are used exclusively in the
Arts & Humanities Citation Index (A&HCI), and not included in our analysis because
A&HCI does not have (hitherto) a Journal Citation Report (Leydesdorff et al. 2011, at
pp. 2417 ff.). Table 1 summarizes the changes.
Whereas previously 18 factors were found most appropriate for explaining the structure
of the aggregated citation matrix, an organization into 19 factors explaining 54.3 % of the
variance is most apt for showing the disciplinary structure of the new matrix. The changes
are mainly in the organization of mathematics. Rafols et al. (2010, at p. 1876) already
noted that ‘‘the position of mathematics (all math subject categories) in the map remains
open to debate. Since different strands of mathematics are linked to different major fields
(medicine, engineering, social sciences), these may show as diverse entities in distant
positions, rather than as a unitary corpus, depending on metrics, classifications, and
clustering algorithms used.’’
In the new overlays, the previous factor of ‘‘Computer Science’’ is divided into two
groups and designated (by us) as ‘‘Computer Science’’ and ‘‘Mathematical Methods.’’
Table 2 provides the subject categories organized within these two compartments. The
other 17 factors could remain similar to the previous classification (Rafols et al. 2010).
As with our previous installation, the base map with the relevant initialization routine
for Pajek (v. 2.05) is available on the internet. The new base map can also be used as input
to VOSviewer (Van Eck and Waltman 2010), but this did not improve the visualization in
the case of 19 clusters. (See for more discussion about the differences between the two
visualization techniques Leydesdorff and Rafols (2012).) However, the clustering algo-
rithm in VOSviewer distinguished four, in our opinion highly meaningful, groups
Table 1 Changes in the organization of subject categories and subject areas between versions 4 and 5 of WoS
WoS version 4 WoS version 5
Subject categories (SCI ? SoSCI) 222 ISI subject
categoriesa
225 WoS subject categories
Abbreviation in the download SC WC
A&HCI 25 ISI subject
categories
26 WoS subject categories
Subject areas \not defined[ 151 subject areas; abbreviated SC
in the download
One of the 225 WC is no longer in use; this is: ‘‘Biology, Miscellaneous’’. Only a single journal (Growth
Development and Aging) is attributed to this category. Although this journal was cited 520 times in 2010 and
is listed with an IF-2010 = 3.000, it is not processed in the Journal Citation Reports (JCR) from the citing
side. In summary, we use the matrix of 224 WCs
a Three additional categories were no longer in use (Rafols and Leydesdorff 2009)
590 L. Leydesdorff et al.
123
(Waltman et al. 2010). The organization into these four groups (biomedical, physical,
environmental, and social sciences) is now provided as another (optional) partition within
the Pajek (.paj) file containing the base map, and is also made available as input to
VOSviewer.
The routine allows the user to make an overlay choosing one of the following two
routes:
1. Within the WoS (v. 5.5), one can ‘‘Analyze Results’’ by clicking at the right top of the
page with search results; choose ‘‘Web of Science Categories’’ among the ranking
options, and export the data into a file ‘‘analyze.txt’’. This file can be read by the
program wc10.exe, and the resulting file ‘‘wc10.vec’’ can be imported into the base
map as a vector.1 The visualization (Draw-Partition-Vector within Pajek) then shows
the overlay (e.g., Fig. 1).
2. The routine wc10.exe also generates three so-called ‘‘map’’-files for VOSviewer:
vos4.csv, vos6.csv, and vos19.csv. (The csv-extension makes these text files also
readable using Excel.) These files generate maps when read into VOSviewer with four,
six, and 19 clusters, respectively (using different colors). The manual of VOSviewer
can be consulted for further options (Fig. 2).
A PowerPoint file is provided at http://www.leydesdorff.net/overlaytoolkit/basemaps.
pptx which allows the user to place the legends on top of the maps and which provides a
few examples; these legends can also be edited. An additional routine enables the user to
measure Rao-Stirling diversity as an index of the interdisciplinarity in the samples under
study (cf. Carley and Porter 2012; Leydesdorff and Rafols 2011; Porter and Rafols 2009;
Rafols et al. 2012; Stirling 2007).
By thus adjusting to the new situation, we hope to have provided the community with a
means to map inter- and multidisciplinary sets of documents in future research using the
new version of the Web of Science (cf. Leydesdorff and Rafols 2009; Melkers and Hicks
Table 2 Distinction between ‘‘computer science’’ and ‘‘mathematical methods’’ in terms of WoS subject
categories
12 WC attributed to ‘‘computer science’’ 6 WCs attributed to ‘‘mathematical methods’’
Computer science, hardware and architecture Computer science, interdisciplinary applications
Engineering, electrical and electronic Operations research and management science
Computer science, artificial intelligence Mathematics, applied
Computer science, theory and methods Statistics and probability
Computer science, information systems Engineering, industrial
Telecommunications Mathematics
Automation and control systems
Computer science, cybernetics
Computer science, software engineering
Robotics
Imaging science and photographic technology
Transportation science and technology
1 The same file ‘‘wc10.vec’’ is automatically generated when using the routine ISI.exe for organizing the
saved output of the WoS, as specified at http://www.leydesdorff.net/software/isi.
Global maps of science 591
123
2012; Porter and Youtie 2009; Soo´s and Kampis 2011). A detailed manual for the mapping
was provided (at the website) by Ken Riopelle. Additionally, a macro to transform the file
‘‘analyze.txt’’ into the Gephi format was provided by Clement Levallois.
Acknowledgments We are grateful to Alan Porter for comments on a previous draft. We acknowledge
Thomson Reuters for the use of the data. We acknowledge support from the ESRC grant RES-360-25-0076.
Fig. 1 Disciplinary composition of 5,793 citable items (articles, proceedings papers, and reviews)
published in 2009 with an address at Oxford University; Rao-Stirling = 0.856. (Pajek used for the
visualization.)
Fig. 2 Disciplinary composition of 5,468 citable items (articles, proceedings papers, and reviews)
published in 2009 with an address at the University of Cambridge; Rao-Stirling = 0.851. (VOSviewer used
for the visualization.)
592 L. Leydesdorff et al.
123
Open Access This article is distributed under the terms of the Creative Commons Attribution License
which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the
source are credited.
References
Carley, S., & Porter, A. L. (2012). A forward diversity index. Scientometrics, 90(2), 407–427.
Leydesdorff, L., Hammarfelt, B., & Salah, A. A. A. (2011). The structure of the Arts & Humanities Citation
Index: A mapping on the basis of aggregated citations among 1,157 journals. Journal of the American
Society for Information Science and Technology, 62(12), 2414–2426.
Leydesdorff, L., & Rafols, I. (2009). A global map of science based on the isi subject categories. Journal of
the American Society for Information Science and Technology, 60(2), 348–362.
Leydesdorff, L., & Rafols, I. (2011). How do emerging technologies conquer the world? An exploration of
patterns of diffusion and network formation. Journal of the American Society for Information Science
and Technology, 62(5), 846–860.
Leydesdorff, L., & Rafols, I. (2012). Interactive overlays: A new method for generating global journal maps
from web-of-science data. Journal of Informetrics, 6(3), 318–332.
Melkers, J., & Hicks, D. (2012). Bibliometrics as a tool for research evaluation. In A. Link & N. Vornatas
(Eds.), Handbook on the Theory and Practice of Program Evaluation. Cheltenham: Edward Elgar.
Porter, A. L., & Rafols, I. (2009). Is science becoming more interdisciplinary? Measuring and mapping six
research fields over time. Scientometrics, 81(3), 719–745.
Porter, A. L., & Youtie, J. (2009). How interdisciplinary is nanotechnology? Journal of Nanoparticle
Research, 11(5), 1023–1041.
Rafols, I., & Leydesdorff, L. (2009). Content-based and algorithmic classifications of journals: Perspectives
on the dynamics of scientific communication and indexer effects. Journal of the American Society for
Information Science and Technology, 60(9), 1823–1835.
Rafols, I., Leydesdorff, L., O’Hare, A., Nightingale, P., & Stirling, A. (2012). How journal rankings can
suppress interdisciplinary research: A comparison between innovation studies and business & man-
agement. Research Policy, 41(7), 1262–1282.
Rafols, I., Porter, A., & Leydesdorff, L. (2010). Science overlay maps: A new tool for research policy and
library management. Journal of the American Society for Information Science and Technology, 61(9),
1871–1887.
Soo´s, S., & Kampis, G. (2011). Towards a typology of research performance diversity: The case of top
Hungarian players. Scientometrics, 87, 357–371.
Stirling, A. (2007). A general framework for analysing diversity in science, technology and society. Journal
of the Royal Society, Interface, 4(15), 707–719.
Van Eck, N. J., & Waltman, L. (2010). Software survey: VOSviewer, a computer program for bibliometric
mapping. Scientometrics, 84(2), 523–538.
Waltman, L., van Eck, N. J., & Noyons, E. (2010). A unified approach to mapping and clustering of
bibliometric networks. Journal of Informetrics, 4(4), 629–635.
Global maps of science 593
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Global maps of science based on the new Web-of-SciencecategoriesLoet Leydesdorff • Stephen Carley • Ismael RafolsReceived: 9 February 2012 / Published online: 17 June 2012 The Author(s) 2012. This article is published with open access at Springerlink.comAbstract In August 2011, Thomson Reuters launched version 5 of the Science and SocialScience Citation Index in the Web of Science (WoS). Among other things, the 222 ISISubject Categories (SCs) for these two databases in version 4 of WoS were renamed andextended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but ata higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbre-viated ‘‘SC’’ in the download, whereas ‘‘WC’’ is used for WoS Categories. Since wepreviously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freelyavailable at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of theAmerican Society for Information Science and Technology 61:1871–1887, 2010) andbrought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibratedthis map for the new WC categories using the Journal Citation Reports 2010. In the newinstallation, the base maps can also be made using VOSviewer (VOSviewer is freelyavailable at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics84:523–538, 2010).Keywords Map  Overlay  Web of Science  Subject categories  InterdisciplinarityL. Leydesdorff (&)Amsterdam School of Communication Research (ASCoR), University of Amsterdam,Kloveniersburgwal 48, 1012 CX Amsterdam, The Netherlandse-mail: loet@leydesdorff.netURL: http://www.leydesdorff.netS. CarleySchool of Public Policy, Georgia Tech, Atlanta, GA, USAe-mail: stephen.carley@gmail.comI. RafolsSPRU (Science and Technology Policy Research), University of Sussex,Freeman Centre, Falmer Brighton, East Sussex BN1 9QE, UKe-mail: i.rafols@sussex.ac.uk123Scientometrics (2013) 94:589–593DOI 10.1007/s11192-012-0784-8The WC categories are sometimes different from the old SCs. For example, the EuropeanJournal of Pharmaceutics and Biopharmaceutics, which was previously classified to theISI SC ‘‘Engineering, Chemical’’ was now assigned to ‘‘Pharmacology and Pharmacy.’’ Inan Annex, Rafols et al. (2010) showed that with aggregated sets the map is relatively robustagainst error in the classifications, but the differences can be significant at lower levels ofaggregation (Rafols and Leydesdorff 2009). As noted, the semantics may be confusing:WoS Subject Categories (WC) replace the old ISI Subject Categories (SC), but the oldlabel SC for Subject Categories is now used in the download for the 151 newly created‘‘Subject Areas’’ as they are called at the WoS interface. Both in the old and the newsituation there are additionally 25 Subject Categories which are used exclusively in theArts & Humanities Citation Index (A&HCI), and not included in our analysis becauseA&HCI does not have (hitherto) a Journal Citation Report (Leydesdorff et al. 2011, atpp. 2417 ff.). Table 1 summarizes the changes.Whereas previously 18 factors were found most appropriate for explaining the structureof the aggregated citation matrix, an organization into 19 factors explaining 54.3 % of thevariance is most apt for showing the disciplinary structure of the new matrix. The changesare mainly in the organization of mathematics. Rafols et al. (2010, at p. 1876) alreadynoted that ‘‘the position of mathematics (all math subject categories) in the map remainsopen to debate. Since different strands of mathematics are linked to different major fields(medicine, engineering, social sciences), these may show as diverse entities in distantpositions, rather than as a unitary corpus, depending on metrics, classifications, andclustering algorithms used.’’In the new overlays, the previous factor of ‘‘Computer Science’’ is divided into twogroups and designated (by us) as ‘‘Computer Science’’ and ‘‘Mathematical Methods.’’Table 2 provides the subject categories organized within these two compartments. Theother 17 factors could remain similar to the previous classification (Rafols et al. 2010).As with our previous installation, the base map with the relevant initialization routinefor Pajek (v. 2.05) is available on the internet. The new base map can also be used as inputto VOSviewer (Van Eck and Waltman 2010), but this did not improve the visualization inthe case of 19 clusters. (See for more discussion about the differences between the twovisualization techniques Leydesdorff and Rafols (2012).) However, the clustering algo-rithm in VOSviewer distinguished four, in our opinion highly meaningful, groupsTable 1 Changes in the organization of subject categories and subject areas between versions 4 and 5 of WoSWoS version 4 WoS version 5Subject categories (SCI ? SoSCI) 222 ISI subjectcategoriesa225 WoS subject categoriesAbbreviation in the download SC WCA&HCI 25 ISI subjectcategories26 WoS subject categoriesSubject areas \not defined[ 151 subject areas; abbreviated SCin the downloadOne of the 225 WC is no longer in use; this is: ‘‘Biology, Miscellaneous’’. Only a single journal (GrowthDevelopment and Aging) is attributed to this category. Although this journal was cited 520 times in 2010 andis listed with an IF-2010 = 3.000, it is not processed in the Journal Citation Reports (JCR) from the citingside. In summary, we use the matrix of 224 WCsa Three additional categories were no longer in use (Rafols and Leydesdorff 2009)590 L. Leydesdorff et al.123(Waltman et al. 2010). The organization into these four groups (biomedical, physical,environmental, and social sciences) is now provided as another (optional) partition withinthe Pajek (.paj) file containing the base map, and is also made available as input toVOSviewer.The routine allows the user to make an overlay choosing one of the following tworoutes:1. Within the WoS (v. 5.5), one can ‘‘Analyze Results’’ by clicking at the right top of thepage with search results; choose ‘‘Web of Science Categories’’ among the rankingoptions, and export the data into a file ‘‘analyze.txt’’. This file can be read by theprogram wc10.exe, and the resulting file ‘‘wc10.vec’’ can be imported into the basemap as a vector.1 The visualization (Draw-Partition-Vector within Pajek) then showsthe overlay (e.g., Fig. 1).2. The routine wc10.exe also generates three so-called ‘‘map’’-files for VOSviewer:vos4.csv, vos6.csv, and vos19.csv. (The csv-extension makes these text files alsoreadable using Excel.) These files generate maps when read into VOSviewer with four,six, and 19 clusters, respectively (using different colors). The manual of VOSviewercan be consulted for further options (Fig. 2).A PowerPoint file is provided at http://www.leydesdorff.net/overlaytoolkit/basemaps.pptx which allows the user to place the legends on top of the maps and which provides afew examples; these legends can also be edited. An additional routine enables the user tomeasure Rao-Stirling diversity as an index of the interdisciplinarity in the samples understudy (cf. Carley and Porter 2012; Leydesdorff and Rafols 2011; Porter and Rafols 2009;Rafols et al. 2012; Stirling 2007).By thus adjusting to the new situation, we hope to have provided the community with ameans to map inter- and multidisciplinary sets of documents in future research using thenew version of the Web of Science (cf. Leydesdorff and Rafols 2009; Melkers and HicksTable 2 Distinction between ‘‘computer science’’ and ‘‘mathematical methods’’ in terms of WoS subjectcategories12 WC attributed to ‘‘computer science’’ 6 WCs attributed to ‘‘mathematical methods’’Computer science, hardware and architecture Computer science, interdisciplinary applicationsEngineering, electrical and electronic Operations research and management scienceComputer science, artificial intelligence Mathematics, appliedComputer science, theory and methods Statistics and probabilityComputer science, information systems Engineering, industrialTelecommunications MathematicsAutomation and control systemsComputer science, cyberneticsComputer science, software engineeringRoboticsImaging science and photographic technologyTransportation science and technology1 The same file ‘‘wc10.vec’’ is automatically generated when using the routine ISI.exe for organizing thesaved output of the WoS, as specified at http://www.leydesdorff.net/software/isi.Global maps of science 5911232012; Porter and Youtie 2009; Soo´s and Kampis 2011). A detailed manual for the mappingwas provided (at the website) by Ken Riopelle. Additionally, a macro to transform the file‘‘analyze.txt’’ into the Gephi format was provided by Clement Levallois.Acknowledgments We are grateful to Alan Porter for comments on a previous draft. We acknowledgeThomson Reuters for the use of the data. We acknowledge support from the ESRC grant RES-360-25-0076.Fig. 1 Disciplinary composition of 5,793 citable items (articles, proceedings papers, and reviews)published in 2009 with an address at Oxford University; Rao-Stirling = 0.856. (Pajek used for thevisualization.)Fig. 2 Disciplinary composition of 5,468 citable items (articles, proceedings papers, and reviews)published in 2009 with an address at the University of Cambridge; Rao-Stirling = 0.851. (VOSviewer usedfor the visualization.)592 L. Leydesdorff et al.123Open Access This article is distributed under the terms of the Creative Commons Attribution Licensewhich permits any use, distribution, and reproduction in any medium, provided the original author(s) and thesource are credited.ReferencesCarley, S., & Porter, A. L. (2012). A forward diversity index. Scientometrics, 90(2), 407–427.Leydesdorff, L., Hammarfelt, B., & Salah, A. A. A. (2011). The structure of the Arts & Humanities CitationIndex: A mapping on the basis of aggregated citations among 1,157 journals. Journal of the AmericanSociety for Information Science and Technology, 62(12), 2414–2426.Leydesdorff, L., & Rafols, I. (2009). A global map of science based on the isi subject categories. Journal ofthe American Society for Information Science and Technology, 60(2), 348–362.Leydesdorff, L., & Rafols, I. (2011). How do emerging technologies conquer the world? An exploration ofpatterns of diffusion and network formation. Journal of the American Society for Information Scienceand Technology, 62(5), 846–860.Leydesdorff, L., & Rafols, I. (2012). Interactive overlays: A new method for generating global journal mapsfrom web-of-science data. Journal of Informetrics, 6(3), 318–332.Melkers, J., & Hicks, D. (2012). Bibliometrics as a tool for research evaluation. In A. Link & N. Vornatas(Eds.), Handbook on the Theory and Practice of Program Evaluation. Cheltenham: Edward Elgar.Porter, A. L., & Rafols, I. (2009). Is science becoming more interdisciplinary? Measuring and mapping sixresearch fields over time. Scientometrics, 81(3), 719–745.Porter, A. L., & Youtie, J. (2009). How interdisciplinary is nanotechnology? Journal of NanoparticleResearch, 11(5), 1023–1041.Rafols, I., & Leydesdorff, L. (2009). Content-based and algorithmic classifications of journals: Perspectiveson the dynamics of scientific communication and indexer effects. Journal of the American Society forInformation Science and Technology, 60(9), 1823–1835.Rafols, I., Leydesdorff, L., O’Hare, A., Nightingale, P., & Stirling, A. (2012). How journal rankings cansuppress interdisciplinary research: A comparison between innovation studies and business & man-agement. Research Policy, 41(7), 1262–1282.Rafols, I., Porter, A., & Leydesdorff, L. (2010). Science overlay maps: A new tool for research policy andlibrary management. Journal of the American Society for Information Science and Technology, 61(9),1871–1887.Soo´s, S., & Kampis, G. (2011). Towards a typology of research performance diversity: The case of topHungarian players. Scientometrics, 87, 357–371.Stirling, A. (2007). A general framework for analysing diversity in science, technology and society. Journalof the Royal Society, Interface, 4(15), 707–719.Van Eck, N. J., & Waltman, L. (2010). Software survey: VOSviewer, a computer program for bibliometricmapping. Scientometrics, 84(2), 523–538.Waltman, L., van Eck, N. J., & Noyons, E. (2010). A unified approach to mapping and clustering ofbibliometric networks. Journal of Informetrics, 4(4), 629–635.Global maps of science 593123

Scientometrics

This article is distributed under the terms of the Creative Commons Attribution License.In August 2011, Thomson Reuters launched version 5 of the Science and Social Science Citation Index in the Web of Science (WoS). Among other things, the 222 ISI Subject Categories (SCs) for these two databases in version 4 of WoS were renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject Areas was added, but at a higher level of aggregation. Perhaps confusingly, these Subject Areas are now abbreviated “SC” in the download, whereas “WC” is used for WoS Categories. Since we previously used the ISI SCs as the baseline for a global map in Pajek (Pajek is freely available at http://vlado.fmf.uni-lj.si/pub/networks/pajek/) (Rafols et al., Journal of the American Society for Information Science and Technology 61:1871–1887, 2010) and brought this facility online (at http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the new WC categories using the Journal Citation Reports 2010. In the new installation, the base maps can also be made using VOSviewer (VOSviewer is freely available at http://www.VOSviewer.com/) (Van Eck and Waltman, Scientometrics 84:523–538, 2010).We acknowledge support from the ESRC grant RES-360-25-0076.Peer Reviewe

Leydesdorff, Loet

Carley, Stephen

Rafols, Ismael

Digital.CSIC

A forward diversity index.

A general framework for analysing diversity in science, technology and society.

A global map of science based on the isi subject categories.

A uniﬁed approach to mapping and clustering of bibliometric networks.

Bibliometrics as a tool for research evaluation.

Content-based and algorithmic classiﬁcations of journals: Perspectives on the dynamics of scientiﬁc communication and indexer effects.

How do emerging technologies conquer the world? An exploration of patterns of diffusion and network formation.

How interdisciplinary is nanotechnology?

How journal rankings can suppress interdisciplinary research: A comparison between innovation studies and business & management.

Interactive overlays: A new method for generating global journal maps from web-of-science data.

Is science becoming more interdisciplinary? Measuring and mapping six research ﬁelds over time.

Science overlay maps: A new tool for research policy and library management.

Software survey: VOSviewer, a computer program for bibliometric mapping.

Towards a typology of research performance diversity: The case of top Hungarian players.

Global Maps of Science based on the new Web-of-Science Categories

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