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Bibliometrics and Altmetrics: Measuring the Impact of Knowledge: Overview of Different Metrics

DEFINITION: Citation Analysis

What is citation analysis?

Citation analysis is the study of the impact and  assumed quality of an article, an author or an institution based on the number of times works and/or authors have been cited by others.

Why use it?

♦  To find out how much impact a particular article has had, by showing which other authors based some work upon it or cited it as an example within their own papers.

♦  To determine how much impact a particular author has had by looking at his/her total number of citations.

♦  To find out more about a field or topic; i.e. by reading the papers that cite a seminal work in that area.

Source: Citation Analysis Guide from University of Michigan. Authors: Paul Grochowski, Barbara Shipman, Deirdre Spencer, Sue Wortman.

Overview of Different Metrics Databases


Web of Science (WOS)


Google Scholar       

Subject Focus         

Science, Technology,
Social Sciences, Arts & Humanities

Science, Technology, Medical, Engineering, Arts & Humanities

Medical, Scientific, Technical, Business, 
Social Sciences, Arts & Humanities


Composed of 3 citation indexes:

Science Citation Index Expanded — back to 1900

Social Sciences Citation Index – back to 1956

Arts & Humanities Citation Index – back to 1975

Conference Proceedings -- back to 1990

Includes the following subjects:

Life Sciences
Health Sciences
Physical Sciences
Social Sciences 
Arts & Humanities

The majority of these titles go back to 2002

Selections from PubMed, IEEE, American Institute of Physics, proceedings of the National Academy of Sciences,, American Medical Association and other medicine journals, Ingenta, SpringerLink,Wiley Interscience, Cambridge journals, Taylor and Francis, Sage Publications, Blackwell-Synergy, OCLC First Search and others

Open access journals and pre-prints

Online dissertations and theses


Over 12,000 journals

19,500 active journals


Time Span

Some journal files going back to 1900; see above for more details

44.4 million records, of which:

29 million records include references going back to 1996 (78% include references)

21 million pre-1996 records go back to 1823

Theoretically, whatever is available on the Web



1-2 Times a week

Monthly on average


Deeper back-files especially for Science Journals.

While controversial, its journal citation reports, impact factors, and h-index are most widely used.

More focused on U.S. research.

Offers citation mapping for visual presentation.

User friendly search interface.

Broader coverage of journals (16, 500 versus 10,000 in WOS).

Downloadable reference list.

More internationally focused than WoS

Includes more than 1,200 Open Access titles.

Provides a more comprehensive picture of scholarly impact as it indexes non-traditional sources such as PowerPoint and MS Word documents not covered by WOS and Scopus.

Includes peer-reviewed papers, theses, books, abstracts, and articles from academic publishers, professional societies, preprint repositories, universities, and other scholarly organizations

Better coverage of newer materials than both WOS and Scopus.

International and multi-lingual coverage.


Can lead to low citation counts due to errors in citations provided by authors, and different citation styles used by journals leading to poor indexing.

Citation tracking is limited to the relatively narrow time span of 1996+.

Not very strong in Social Science and Arts & Humanities coverage.

Limited search features.

Inflated citation counts due to inclusion of non-scholarly sources such as promotional pages, table of contents pages, course readings lists etc.

Weeding irrelevant hits is time consuming.

No way to determine what sources, and time spans are covered.

Limited to what is available on the free Web.

May include non-scholarly citations like newspaper articles.

Source: Citation Analysis Guide from University of Michigan. Authors: Paul Grochowski, Barbara Shipman, Deirdre Spencer, Sue Wortman.