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Last Update
- 5 December 2014
Introduction
See also Altmetrics |
Author impact metrics |
Google scholar |
Impact factors |
Research Portal for Academic Librarians |
Scirus |
Webometrics
" ...the ThomsonReuters Web of Science 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"...Web of Science (WOS) from Thomson Reuters (TR) is a
multidisciplinary abstracting and indexing resource with 22 separate
components to which institutions can subscribe in any combination.
Journal indexing is cover-to-cover for 16,959 titles including 726 open
access publications... — Goodwin, 2014
Elsevier's Scopus and
Thomson Reuter's Web of Science (WoS) are the two most extensive, popular (and commonly-used) search tools in academia to track
impact factors. (For direct head-to-head comparisons,
see this
Scopus and Web of Science Comparison Chart.)
Besides searching the literature, these two databases are rank journals
in terms of productivity and total # of citations received to indicate
their impact, prestige and influence. The principles behind
bibliometrics, and
cited reference searching, are used to track impact of authors, their scholarship, and where they opt to publish.
Scopus and WoS, though complementary, are quite different tools.
If researchers or librarians were asked to select one, which do they
prefer? To answer this, the two databases should be compared for
qualitative and quantitative aspects. Both use
bibliometrics
but each has unique features, coverage and practices. Scopus has more
content (~22,000 journals) but comes with a noticeable European and
Elsevier-publisher bias. The WoS covers ~12,000 journals (
open access
titles and conference abstracts) but reveals its own American bias.
Academic libraries provide access to either Scopus or WoS, but rarely
both.
In further detail,
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 science literature. While several databases such as
EBSCO offer a kind of internal
cited reference searching their coverage is not as comprehensive as the
WoS.
In fact, it can be said with some certainty that no single tool is able
to track all citations and the research citing them. The databases that
offer cited reference searching often focus on academic journals that
they index and neglect papers in the deep web (
see grey literature). As a result, some important seminal articles and monographs are always missed.
Dr. Peter Jacso criticizes the claims of those who use Scopus, WoS and
Google scholar pointing 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!
Scopus
Subject coverage in Scopus<center> Scopus indexes 53 million records, 21,915 titles and content from 5,000 publishers, and claims to be the
largest abstract and citation database of research literature and quality web sources. This claim is challenged by researchers in various fields including in library science (Jacso, 2011).
See this breakdown of
Scopus content. Elsevier is the owner of Scopus and is also one of the main international publishers of scientific journals.
- Scopus contains 53 million records, 70% with abstracts
- Nearly 22,000 titles from 5,000 publishers worldwide
- 4.9 million conference proceedings, 1,200 Open Access journals
- 100% Medline coverage
- 20+ million records back to 1996 with references
- 20+ million pre-1996 records go back as far as 1869
- 40,000 monographs or books
- 386 million scientific web pages
- 22 million patent records from 5 patent offices
- Links to full-text & other library resources
- Innovative tools to review results and refine to relevant hits
- Alerts to keep you up-to-date on new articles matching your search query, or by favorite authors
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.
Benefits & weaknesses
- Scopus permits search by affiliation; by zip code and institutional name(s).
- Scopus covers over 22,000 journals, versus 11,000 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 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) (formerly
Web of Knowledge)
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.
Summary:
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.
Google Scholar
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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