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Tools to measure journal impact

Some journals are read and cited more than others.
Measuring the impact of a journal may help you identify where to publish, to identify journals relevant to your research and to confirm the status of journals in which you have published. It is important to note that journal impact measures vary among research disciplines due to differing citation behavior and thus cannot be directly compared¹.

Use journal-based metrics with care!

The San Francisco Declaration on Research Assessment (DORA) recommends not to "use journal-based metrics, such as Journal Impact Factors, as a surrogate measure of the quality of individual research articles, to assess an individual scientist's contribution, or in hiring, promotion, or funding decisions" (see http://am.ascb.org/dora/).

Be aware that ....

  • Many journals do not have an impact factor 
  • The impact factor cannot assess the quality of individual articles. Even if citations were evenly distributed among articles, the impact factor would only measure the interests of other researchers in an article, not its importance and usefulness
  • Only research article, technical notes and reviews are 'citable' items. Editorials, letters, news items and meeting abstracts are not always citable
  • Only a small percentage of articles are highly cited and they are found in a small subset of journals. This small proportion accounts for a large percentage of citations
  • Controversial papers, such as those based on fraudulent data, may be highly cited, distorting the impact factor of a journal
  • Citation bias may exist. For example, English language resources may be favoured. Authors may cite their own work
  • Use more than one tool!

From: Measuring research impact - subject guides at Queensland University of Technology

 

Journal-based metrics

The most used indication of the success of a journal is the Journal Impact Factor (JIF) from ISI Web of Knowledge (Thomson Reuters). The impact factor is a measure of the frequency with which the average article in a journal has been cited in a particular year or period².
For example, the 2009 Impact Factor is calculated by taking the number of citations made in 2009 to articles published in the journal in 2007 and 2008 divided by the total number of that journal's 2007 and 2008 articles¹.

There are several tools available to measure journal impact. These can be divided in subscription databases and publicly accessible websites. EUR researchers can access both categories with an ERNA-account.

Subscription databases

Citation data on journals in the areas of science, technology, and social sciences.
Each annual database contains the citation data from the JCR year indicated. (current = 2009). For every journal covered, the following information is collected or calculated:

* Citation and article counts;
* Impact factor;
* Immediacy index;
* Cited half-life;
* Citing half-life;
* Source data listing;
* Citing journal listing;
* Cited journal listing;
* Subject categories;
* Publisher information.

Example of the journal 'Scientific American' in ISI Journal Citation Reports. Click here.
  • Scopus *-  Journal Analyzer

The Scopus Journal Analyzer provides a view of journal performance. Access via the 'Analytics button' on the opening screen of the Scopus database. With citations from over 18,000 peer-reviewed journals from 5,000 publishers, the Scopus Journal Analyzer enables you to compare up to 10 journals simultaneously, back to 1996 . Two journal metrics – 'SCImago Journal Rank' (SJR) and 'Source Normalized Impact per Paper' (SNIP) are being used. These metrics cover: “journal prestige and contextual citation impact, providing comprehensive journal evaluation across all scientific disciplines.”

  • Source Normalized Impact per Paper (SNIP) measures contextual citation impact by weighting citations based on the total number of citations in a subject field. The impact of a single citation is given higher value in subject areas where citations are less likely, and vice versa.
  • SCImago Journal Rank (SJR), is a measure of the scientific prestige of scholarly sources: value of weighted citations per document. A source transfers its own 'prestige', or status, to another source through the act of citing it. A citation from a source with a relatively high SJR is worth more than a citation from a source with a lower SJR.

View the tutorial on how to use use the Scopus Journal Analyzer.
View the video on how SNIP and SJR are calculated.

Publicly accessible websites

Eigenfactors are calculated by eigenfactor.org where they can be freely reviewed. 'Eigenfactor scores' and 'Article Influences scores' rank journals with algorithms using the structure of the entire citation network (adjusting for citation differences across disciplines) to evaluate the importance of each journal.

  • Eigenfactor™ Score (EF): a measure of the overall value provided by all of the articles published in a given journal in a year.
  • Article Influence™ Score (AI): a measure of a journal's prestige based on per article citations and comparable to Impact Factor.

Eigenfactor™ Score and Article Influence™ Score: Frequently Asked Questions

* The subscription databases of the Erasmus University Library are only available for EUR staff and students with a VPN-connection and ERNA account.

¹  University of Minnesota University Libraries, Research Impact Measures, Retrieved December 14, 2010 from http://www.lib.umn.edu/researchsupport/impact 

² Thomson Reuters, The Thomson Reuters impact factor, Retrieved December 14, 2010 from http://thomsonreuters.com/products_services/science/free/essays/impact_factor/