COCHRANE DATABASE OF SYSTEMATIC REVIEWS

INDEXING, CITATIONS & BIBLIOMETRICS

Adam FinchBibliometrics Analyst

Impact Factor: Meaning & Calculation

Impact Factor for JCR Year x = Citations in Year x to Papers from x-1 and x-2

Number of Source Items in x-1 and x-2

Cites in 2009 to articles published in:2008 = 2592  Number of articles published in: 2008 = 526   2007 = 3982    2007 = 637   Sum: 6574    Sum: 1163 

Calculation:  Cites to recent articles  6574 =  5.653Number of recent articles  1163 

NB: Source Items are Articles, Reviews and Proceedings Papers; only these papers contribute to the denominator. Citations counted on the numerator, however, can be to any document type.

• Evaluates the impact of a journal based on a citation as a unit of quality • Based on ISI’s Web of Science and released in an annual Journal Citation Report• Essentially a measure of average citations per article

– Inconsistent standards for inclusion

Impact Factor: Strengths & Weaknesses

– Affected by ‘ citation inflation’

– Error correction difficult

– Subject area dependency

– Self-citation open to manipulation

+ Average cites-per-article makes sense

+ Comparatively easy to understand

+ Can be duplicated, predicted and simulated

+ Established and recognised metric

+ Broken down into ranked subject categories

2010 Impact Factor

2008 2009 ChangeImmediacy Index 1.131 1.311 15.9%Immediacy Index for Medicine, General & Internal 1.295 1.171 -9.6%

The Impact Factor will probably rise next year. 2010 IF looks at 2010 cites to 2009 and 2008 papers.

The Immediacy Index looks at citations in a given year to articles published in the same year.E.g. 2009 cites to 2009 papers ÷ # 2009 papers. A rise can indicate a strong year of papers.

Web of Science

Web of Science

Web of Science: Journal Data

• Bibliographic data (author, address, title, keywords, etc)

• Digital Object Identifier (DOI)

• Citation Report listing citations received each year since publication

• Client Article Reference (CD & Pub Numbers)

• Unique identifier for article with date of publication and page numbers

Web of Science: Cochrane Database of Systematic Reviews

• Bibliographic data (author, address, title, keywords, etc)

• Digital Object Identifier (DOI)

• Citation Report listing citations received each year since publication

• Client Article Reference (CD & Pub Numbers)

• Unique identifier for unique article with date of publication

Web of Science: Acquiring and Repairing the Data• Manually edit ISI article list of 2005—2008 papers so it matches actual content

• Match 15,000 citations to 2,431 target articles using:- Cited DOI Cited Article Reference Unique author in year

• Download all reviews in ISI subject category and process through in-house tools

• Search for and download all citations to CDSR for the past several years

• Add Review Group data from Editorial Office records

Author Document Type Region

Institution Country Review Group

Citation Incidence Citing Characteristics Top Cited Articles

• Analysis and reporting took days... Data acquisition and cleanup took weeks...

Analysis Highlights: CDSR

• Author loyalty. Of the 863 authors publishing reviews in CDSR that contributed to the 2009 Impact Factor, only 11 had more highly cited papers published elsewhere.

• Index comparison. Unfortunately, Elsevier’s Scopus does not provide a useful alternative data source.

The Scopus citation matching algorithm finds even fewer cites than WoS, despite looking at twice the number of citing journals.

Scopus contains a larger number of duplicate version entries due to the erroneous addition of variant Pubmed data to the records supplied by Wiley-Blackwell.

• Standard analyses less useful for CDSR.

Analysis Highlights: CDSR

Analysis Highlights: CDSR

Analysis Highlights: Subject Category

Thank you

Any questions or feedback?

E-mail: burquhart@wiley.com