Citation Searching Comparing Web of Science, Google Scholar and Scopus Valerie Forrestal, Stevens Institute of Technology 11-12-08

Citation Databases Meho&Yang http://www.info.scopus.com/detail/what/ http://isiwebofknowledge.com/currentuser_wokhome/cu_productspecs/ Source Unknown 1996-present (with cited references) 1823-present (without cited references) A&HCI: 1975-present SCI: 1900-present SSCI: 1956- present Coverage years 500M records Unknown 30+ document types 36M records 16,000 titles Journals (1200 open access), Conference Proceedings, Trade Publications & book series 40M records 10,000 titles Journals (240 open access) & conference papers Breadth of coverage Google Scholar Scopus Web of Science

Source : Hull, D., Pettifer, S.R., & Kell, D.B. (2008). Defrosting the Digital Library: Bibliographic Tools for the Next Generation Web. PLoS Computational Biology 4(10): e1000204 doi:10.1371/journal.pcbi.1000204

Content: Scopus has almost 36 million record and WoS -including backfiles- 40 million. Scopus includes 16,000 journal titles against almost 10,000 in WoS. Coverage : preliminary conclusions: Scopus has after 1996 about 30% more, and before that about 10% less coverage than WoS Coverage in biology, environmental science, engineering and computer science very good in Scopus Coverage in health sciences also very good, but doubt over most recent years Coverage psych, anthropology, economics and chemistry acceptable, but before 1996 there are several gaps Coverage in physics, astronomy, math and sociology less reliable Not-so-great coverage philosophy, theology, arts and literature Up-to-dateness: there is hardly any difference between WoS-Scopus considering the speed of updating records Citation details: again the difference is rather small, there is a large overlap between WoS-Scopus, but the difference with Google Scholar is larger and it finds more unique publications. Speed: Google Scholar is faster than WoS or Scopus. WoS has the disadvantage of being a little slower than Scopus. Opinions : most "power users" like the Scopus interface and value the Refine and Citation Tracker, but it can not replace -for the time being- the Journal Citation Reports. Source : Bosman, J., I.v. Mourik, M. Rasch, E. Sieverts & H. Verhoeff (2006). Scopus reviewed and compared; the coverage and functionality of the citation database Scopus, including comparisons with Web of Science and Google Scholar. ( http://igitur-archive.library.uu.nl/DARLIN/2006-1220-200432/Scopus%20doorgelicht%20&%20vergeleken%20-%20translated.pdf ) – includes updated info. -vf.

Content: Scopus has almost 36 million record and WoS -including backfiles- 40 million. Scopus includes 16,000 journal titles against almost 10,000 in WoS.

Coverage : preliminary conclusions:

Scopus has after 1996 about 30% more, and before that about 10% less coverage than WoS

Coverage in biology, environmental science, engineering and computer science very good in Scopus

Coverage in health sciences also very good, but doubt over most recent years

Coverage psych, anthropology, economics and chemistry acceptable, but before 1996 there are several gaps

Coverage in physics, astronomy, math and sociology less reliable

Not-so-great coverage philosophy, theology, arts and literature

Up-to-dateness: there is hardly any difference between WoS-Scopus considering the speed of updating records

Citation details: again the difference is rather small, there is a large overlap between WoS-Scopus, but the difference with Google Scholar is larger and it finds more unique publications.

Speed: Google Scholar is faster than WoS or Scopus. WoS has the disadvantage of being a little slower than Scopus.

Opinions : most "power users" like the Scopus interface and value the Refine and Citation Tracker, but it can not replace -for the time being- the Journal Citation Reports.

Scopus and WoS: Citation Count Scopus vs. WoS 14.0% (278) more citations by Scopus More comprehensive coverage by Scopus (15,000 vs. 8,700 periodicals) Scopus + WoS Scopus increases WoS citations by 35% (710) WoS increases Scopus citations by 19.0% (432) Relatively low overlap (58%) and high uniqueness (42%) Scopus (2,301) Web of Science (2,023) 58% (1,591) 26% (710) 16% (432) Scopus  WoS (2,733) Source : Meho & Yang

Scopus vs. WoS

14.0% (278) more citations by Scopus

More comprehensive coverage by Scopus (15,000 vs. 8,700 periodicals)

Scopus + WoS

Scopus increases WoS citations by 35% (710)

WoS increases Scopus citations by 19.0% (432)

Relatively low overlap (58%) and high uniqueness (42%)

GS vs. Scopus  WoS GS increases WoS  Scopus citations by 93% (2,552) Scopus  WoS increases GS citations by 26% (1,104) GS identifies 53% (or 1,448) more citations than WoS  Scopus GS has much better coverage of conference proceedings (1,849 by GS vs. 496 by Scopus  WoS) GS has over twice as many unique citations as Scopus  WoS (2,552 vs. 1,104, respectively) Google Scholar (4,181) Scopus  WoS (2,733) 31% (1,629) 48% (2,552) 21% (1,104) GS  Scopus  WoS (5,285) Source : Meho & Yang

GS increases WoS  Scopus citations by 93% (2,552)

Scopus  WoS increases GS citations by 26% (1,104)

GS identifies 53% (or 1,448) more citations than WoS  Scopus

GS has much better coverage of conference proceedings

(1,849 by GS vs. 496 by Scopus  WoS)

GS has over twice as many unique citations as Scopus  WoS

(2,552 vs. 1,104, respectively)

Meho & Yang’s Findings Scopus, WoS, and GS complement rather than replace each other GS can be useful in showing evidence of broader international impact than could possibly be done through Scopus and WoS GS can be very useful for citation searching purposes; however, it is not conducive for large-scale comparative citation analyses Multiple sources of citations should be used to generate accurate citation counts and rankings Citation databases complement one another Small overlap between sources may significantly influence relative ranking citation coverage varies by research area, document type, language

Scopus, WoS, and GS complement rather than replace each other

GS can be useful in showing evidence of broader international impact than could possibly be done through Scopus and WoS

GS can be very useful for citation searching purposes; however, it is not conducive for large-scale comparative citation analyses

Multiple sources of citations should be used to generate accurate citation counts and rankings

Citation databases complement one another

Small overlap between sources may significantly influence relative ranking

citation coverage varies by research area, document type, language

Common Citation Searching Problems Misspellings. Uncommon spellings/languages/special symbols Author name variations Incorrect citations (for example, year, volume number, inconsistencies of abbreviation). Author order – may only be cited by the first author. Self-citations. Monographic literature is not well covered.

Misspellings.

Uncommon spellings/languages/special symbols

Author name variations

Incorrect citations (for example, year, volume number, inconsistencies of abbreviation).

Author order – may only be cited by the first author.

Self-citations.

Monographic literature is not well covered.

Database Strengths Scopus ’ strengths: interface design/search features recent content (post 1996) the sciences (especially STM) conference proceedings openURL compliant WoS ’ strengths: humanities coverage older publications journal citation reports/impact factors/h-index Google Scholar ’s strengths: number of articles found international/multilingual coverage better coverage of citations in books and other non-journal sources

Scopus ’ strengths:

interface design/search features

recent content (post 1996)

the sciences (especially STM)

conference proceedings

openURL compliant

WoS ’ strengths:

humanities coverage

older publications

journal citation reports/impact factors/h-index

Google Scholar ’s strengths:

number of articles found

international/multilingual coverage

better coverage of citations in books and other non-journal sources

Database Weaknesses Scopus ’ weaknesses: humanities content (also math, physics and business/management) older articles (pre 1996) WoS ’ weaknesses: limited coverage (very few non-ISI-listed/non-English/open access sources) expensive back-files poor external linking capabilities (links are long and contain session ID) Google Scholar ’s weaknesses: very few advanced search/limit/sort features inclusion of non-scholarly sources significantly more time needed to weed/check sources lack of transparency regarding source selection, number of documents, coverage, indexing, etc. difficult to export citations incorrect citations from improper scans

Scopus ’ weaknesses:

humanities content (also math, physics and business/management)

older articles (pre 1996)

WoS ’ weaknesses:

limited coverage (very few non-ISI-listed/non-English/open access sources)

expensive back-files

poor external linking capabilities (links are long and contain session ID)

Google Scholar ’s weaknesses:

very few advanced search/limit/sort features

inclusion of non-scholarly sources

significantly more time needed to weed/check sources

lack of transparency regarding source selection, number of documents, coverage, indexing, etc.

difficult to export citations

incorrect citations from improper scans

Sources Bauer, K., & Bakkalbasi, N. (2005). An examination of citation counts in a new scholarly communication environment. D-Lib Magazine , 11(9). ( http://dlib.org/dlib/september05/bauer/09bauer.html ) Bosman, J., Mourik, I.v. Rasch, Sieverts, M. E., & Verhoeff, H. (2006). Scopus reviewed and compared; the coverage and functionality of the citation database Scopus, including comparisons with Web of Science and Google Scholar. ( http://igitur-archive.library.uu.nl/DARLIN/2006-1220-200432/Scopus%20doorgelicht%20&%20vergeleken%20-%20translated.pdf ) Harzing, A. W. K., & van der Wal, R. (2008) .Google Scholar as a new source for citation analysis, Ethics in Science and Environmental Politics , 8. ( http://www.int-res.com/articles/esep2008/8/e008pp5.pdf ) Hull, D., Pettifer, S.R., & Kell, D.B. (2008). Defrosting the Digital Library: Bibliographic Tools for the Next Generation Web. PLoS Computational Biology 4(10): e1000204 doi:10.1371/journal.pcbi.1000204 Meho, L.I., & Yang, K. (2007, preprint). A new era in citation and bibliometric analyses: Web of Science, Scopus, and Google Scholar. Journal of the American Society for Information Science and Technology . ( http://arxiv.org/ftp/cs/papers/0612/0612132.pdf )

Bauer, K., & Bakkalbasi, N. (2005). An examination of citation counts in a new scholarly communication environment. D-Lib Magazine , 11(9). ( http://dlib.org/dlib/september05/bauer/09bauer.html )

Bosman, J., Mourik, I.v. Rasch, Sieverts, M. E., & Verhoeff, H. (2006). Scopus reviewed and compared; the coverage and functionality of the citation database Scopus, including comparisons with Web of Science and Google Scholar. ( http://igitur-archive.library.uu.nl/DARLIN/2006-1220-200432/Scopus%20doorgelicht%20&%20vergeleken%20-%20translated.pdf )

Harzing, A. W. K., & van der Wal, R. (2008) .Google Scholar as a new source for citation analysis, Ethics in Science and Environmental Politics , 8. ( http://www.int-res.com/articles/esep2008/8/e008pp5.pdf )

Hull, D., Pettifer, S.R., & Kell, D.B. (2008). Defrosting the Digital Library: Bibliographic Tools for the Next Generation Web. PLoS Computational Biology 4(10): e1000204 doi:10.1371/journal.pcbi.1000204

Meho, L.I., & Yang, K. (2007, preprint). A new era in citation and bibliometric analyses: Web of Science, Scopus, and Google Scholar. Journal of the American Society for Information Science and Technology . ( http://arxiv.org/ftp/cs/papers/0612/0612132.pdf )