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- 30 August 2013
See also Altmetrics | Author impact metrics | Google scholar | Impact factors | Research Portal for Academic Librarians | Scirus | Webometrics
" ...the ThomsonReuters impact factor (TRIF) is a viable, widely used and informative measure of journal visibility and frequency of use..." — Pudovkin & Garfield, 2012
"...between Google scholar and Scopus citations, a combination of the two is recommended [for citation data] rather than just one of them..." — Kousha et al, 2011
'Sciverse' Scopus and Web of Science (WoS) are two popular tools used to track the impact of academics and their research. The field of bibliometrics, and cited reference searching, is focussed on the tracking of major journals, authors and their scholarly impact. Two of the best tools for this purpose are Thomson Reuter's Web of Science (WoS) and Elsevier's "Sciverse" Scopus, both of which can be accessed via subscription. However, the two databases could not be more different. Both use the principles of bibliometrics but each has unique features and coverage. Scopus has more content (~19,500 journals) than WoS and a noticeable European (Elsevier) bias. WoS covers ~12,000 journals (and a number of open access titles and conference abstracts) with an American bias. Most academic libraries provide access to either Scopus or WoS; some libraries subscribe to both. Tracking citations and who cites whom is common in the academic community, and researchers typically find related research in their discipline by tracking who is citing whom (which papers, books chapters or monographs).
WoS is a multidisciplinary database that contains the Science Citation Index, Social Sciences Citation Index and Arts & Humanities Citation Index. Scopus provides access to scientific, technical, medical and social sciences literature for 19,500 journals. Several EBSCO databases offer cited reference searching but their coverage will not be as comprehensive as the WoS. No single tool tracks all occurrences of every citation. Databases that offer cited reference searching often focus on academic journals and those in the deep web (see grey literature). As a result, some important seminal articles and monographs may not be included.
Well-known LIS professor, Peter Jacso, has criticized the claims of those who use Scopus, WoS and Google scholar for bibliometric purposes. He points out that " ...knowing the bibliometric features of databases, their own h-index and related metrics versus those of the alternative tools can be very useful for computing a variety of research performance indicators. However, we need to learn much more about our tools in our rush to metricise everything before we can rest assured that our gauges gauge correctly or at least with transparent limitations...". In light of the ubiquity of new author impact metrics, his statements have a resounding ring of truth to them. In other words: librarians beware!
"Sciverse" Scopus claims to be the largest abstract and citation database of research literature and quality web sources. This claim has been challenged (Jacso, 2011).
- Scopus contains 47 million records, 70% with abstracts
- Over 19,500 titles from 5,000 publishers worldwide
- Includes over 4.9 million conference proceedings, 1,200 Open Access journals
- Scopus provides 100% Medline coverage
- 20+ million records back to 1996 with references
- 20+ million pre-1996 records go back as far as 1869
- Results from 386 million scientific web pages
- 22 million patent records from 5 patent offices
- Seamless links to full-text articles and other library resources
- Innovative tools that review search results and refine to most relevant hits
- Alerts to keep you up-to-date on new articles matching your search query, or by favorite author
Sciverse Scopus covers 250 million quality web sources, including 22 million patents. Searches in Scopus incorporate searches of scientific web pages through Scirus, and include author homepages, university sites and resources such as preprint servers and OAI compliant resources.
Scopus - Benefits & weaknesses
- Scopus permits search by affiliation; by zip code and institutional name(s).
- Scopus covers over 15,000 journals, versus 10,000 in WoS.
- Scopus is 5-15% smaller prior to 1996, and 20-45% larger than WoS after 1996. For publications before 1996, the coverage offered by Scopus for the various subjects is uneven.
- 95% of Scopus' database consists of records of descriptions of articles.
- Before 1996, the number of non-journal articles in Scopus is low; this rises to about 10% by 2005.
- For recent years, the proportion of non-journal articles is significantly higher in Scopus than in WoS (4%).
- Scopus is a more versatile search tool; clear advantages in functionality;
- default, refine, format of results of citation tracker and author identification.
- Scopus covers mostly scientific fields; relatively weak in sociology, physics and astronomy.
Web of Science
Thomson Reuter's Web of Science (WoS) provides access to a network of scholarly articles linked by their references. Articles have been indexed from journals since 1960 and 12,000 journals are currently covered. WoS is the online version of the Science Citation Index with some differences. Separate annual editions covering science, social sciences, and the arts and humanities have been integrated into a multiyear multidisciplinary system. WoS covers nearly 23 million source papers from the 1940s to the present, and frequently updated.
see 2011 Tutorials, 8-minute webinar with downloadable slides & Summary of new features & training links
Web of Science is updated with approximately 25,000 articles and 700,000 cited references added each week.
- Covers 12,311+ journals from 256 categories, 110,000 proceedings from conferences, symposia, seminars, colloquia worldwide
- Journal backfiles to 1900, cover-to-cover indexing, cited reference and chemical structure searches
- Science – 7100 international journals and highly cited book series in 170 categories back to 1900
- Social Sciences – 1,750 international journals and highly cited book series in 50 subject categories back to 1954
- Arts & Humanities – 1,200 international journals and highly cited book series in 25 categories back to 1975
- Complete backfiles to 1945 however put total at ~37 million records
- Cited reference and chemical structure searches
- Author identification tools
- Analysis capabilities
- Direct links to your full-text collections
- Index Chemicus®: Over 2.6 million compounds, to 1993
- Current Chemical Reactions®: Over one million reactions, to 1986, plus INPI archives from 1840 to 1985.
WoS provides unique search methods and cited searching. Users can navigate forward and backward through the literature, and search all disciplines and time periods. Users can navigate to print and electronic collections using institutional linkresolvers.
Web of Science (WoS) is searchable with complete bibliographic data, cited reference data and navigation and links to full text.
Thomson Reuters Impact Factor
JCR provides quantitative tools for ranking, evaluating, categorizing, and comparing journals. The impact factor is one of these; it is a measure of the frequency with which the "average article" in a journal has been cited in a particular year or period. The annual JCR impact factor is a ratio between citations and recent citable items published. Thus, the impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years.
- A = total cites in 2010
- B = 2010 cites to articles published in 2008-9 (a subset of A)
- C = number of articles published in 2008-9
- D = B/C = 2010 impact factor
WoS - Benefits & weaknesses
- Only a slight difference in coverage between Scopus and Web of Science (WoS) and a strong overlap.
- WoS covers science and arts/humanities.
- WoS search interface is improving but not as useful as Scopus.
- WoS has more options for citation analysis for institutions.
- Substantial differences exist between WoS, Scopus and Google scholar - the latter delivers instant results for searchers. This can (subconsciously) be a major reason for users to choose it over other tools.
- Google scholar is much larger than either WoS or Scopus but it has been shown to have fewer references to selected articles. However, GS' unique coverage and web crawling techniques means that it has been shown to have five (5) times as many unique cited items although many counts are inflated.
See also Google scholar bibliography
Google scholar is easy-to-search, provides quick entry into the grey literature and access to cited papers. Jacso says that GS' poor quality control and inflated citation counts however makes it nearly unusable for bibliometric purposes. A number of Impact factors - such as the h-index - are now determined by using Google scholar data despite its many limitations, metadata problems and inflated citation counts. Although Google scholar provides access to other papers through its cited by feature it is generally seen to be a browsing or discovery tool not a properly curated bibliometric tool like WoS or Scopus. Reliable bibliometric searching requires better tools that employ cited reference searching based on accurate counts.
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