Citation Searching

Comparing Web of Science, Google Scholar and Scopus

Valerie Forrestal, Stevens Institute of Technology

11-12-08

Citation DatabasesWeb of Science Scopus Google

Scholar

Breadth of coverage

40M records10,000 titlesJournals (240 open access) & conference papers

36M records16,000 titles Journals (1200 open access), Conference Proceedings, Trade Publications & book series

500M recordsUnknown30+ document types

Coverage years

A&HCI: 1975-presentSCI: 1900-presentSSCI: 1956-present

1996-present (with cited references) 1823-present (without cited references)

Unknown

Source http://isiwebofknowledge.c

om/currentuser_wokhome/cu_productspecs/

http://www.info.scopus.com/detail/what/

Meho&Yang

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.

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

GS vs. ScopusWoS

GS increases WoSScopus citations by 93% (2,552) ScopusWoS increases GS citations by 26% (1,104) GS identifies 53% (or 1,448) more citations than WoSScopus GS has much better coverage of conference proceedings

(1,849 by GS vs. 496 by ScopusWoS) GS has over twice as many unique citations as ScopusWoS

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

Google Scholar(4,181)

ScopusWoS(2,733)

31%(1,629)

48%(2,552)

21%(1,104)

GS ScopusWoS(5,285) Source: Meho &

Yang

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

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.

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

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

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)