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Bibliometrics: a Practical Guide

Journal-level indicators

Journal level indicators

There are several factors that might influence where you decide to publish:
•  the appropriateness of the journal  for the research
•  the status of the journal amongst peers
•  the likelihood of being accepted for the journal
• the quality of the editorial process
•  the speed of publication
•  the openness of the journal ... etc.

What you need to know

It is possible to use journal level indicators to help you target highly cited journals for your own publications but they should be used in the appropriate context and not in isolation.

Remember: Your supervisor or colleagues in your department may be able to help you identify journals to publish in. You must also consider any open access requirements placed by your funder.

The Think.Check.Submit site allows researchers to run some basic checks to see if the journal they intend to submit to is valid and credible.

For more information on the limitations and best uses of journal level indicators see our Information for Researchers web pages on Citation analysis and bibliometrics.

Journal indicators in the arts and humanities

Journal ranking, impact factor and citation indicators are not well-developed in arts and humanities disciplines due to differing trends and practices in research and scholarly communication.

Journals included in the Arts & Humanities Citation Index (AHCI) are not included in Journal Citation Reports and therefore do not receive Impact Factors. Arts and humanities journals exhibit a citation pattern very different from science and social science journals, and are not well suited for an indicator such as the JIF.

The European Reference Index for the Humanities (ERIH) is an attempt to produce a database of significant journals in the humanities. However, ERIH has proved highly controversial; see the article Journals under threat: a Joint response from History of Science, Technology and Medicine editors as an example.

Alternative indices

The Journal Impact Factor (JIF) is the most well known indicator but others are now available which attempt to take account of variations between subject areas and time periods.

5-Year Journal Impact Factor The average number of times articles from the journal published in the past five years have been cited in the Journal Citation Reports (JRC) year. Calculated by dividing the number of citations in the JCR edition year by the total number of articles published in the five previous years.

Article Influence Measures the relative importance of the journal on a per-article basis. The Eigenfactor score divided by the number of articles published in the journal. The scores are normalized so that the mean article in the entire JRC database has an article influence score of 1.00. A score greater than 1.00 suggests that each article in the journal has above-average influence.

CiteScore Calculates the average number of citations received in a calendar year by all items published in that journal in the preceding three years. For example: the 2015 CiteScore counts the citations received in 2015 to documents published in 2012, 2013 or 2014, and divides this by the number of documents indexed in Scopus published in those same three years. New metric, released in December 2016.

Eigenfactor The Eigenfactor Score calculation is based on the number of times articles from the journal published in the past five years have been cited in the JCR year, but it also considers which journals have contributed these citations so that highly cited journals will influence the network more than lesser cited journals. It counts citations to journals in both the sciences and social sciences. Citations from one article in a journal to another article from the same journal are removed, so that Eigenfactor scores are not influenced by journal self-citation.

Normalized Eigenfactor (new) Rescales the Eigenfactor score so that the average journal has a score of 1. Journals can then be compared and measured by their score relative to 1; a journal with a Normalized Eigenfactor Score of 3 suggests that it is three times as good the average journal in the JCR.

h5-index This metric is based on the articles published by a journal over five calendar years. h is the largest number of articles that have each been cited h times. A journal with an h5-index of 43 has published, within a 5-year period, 43 articles that each have 43 or more citations.

IPP (Impact Per Publication) The impact per publication, calculated as the number of citations given in the present year to publications in the past three years divided by the total number of publications in the past three years. IPP is fairly similar to the JIF. Like the JIF, IPP does not correct for differences in citation practices between different disciplines. IPP was previously known as RIP (Raw Impact per Publication).

Journal Cited Half-Life The median age of the citations received by a journal during the JCR year. If a journal's cited half-life is 4.6, this means that half the citations it earned were to items published 4.6 or fewer (JRC) years ago and half were to items published longer ago than that. It may be used to estimate how long a paper published by a specific journal will continue to be cited.

Journal Immediacy Index The average number of times an article is cited in the year it is published. It indicates how quickly articles in a journal are cited. It is published annually in Journal Citation Reports.

SJR An abbreviation for SCImago Journal Rank, the SJR doesn't consider all citations of equal weight; the prestige of the citing journal is taken into account. SJR is based on Scopus citation data.

SNIP An abbreviation for 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.

Journal Impact Factor (JIF)

The Journal Impact Factor (JIF) is the original journal ranking indicator for journals in science and social science disciplines. It uses citation data from the Web of Science database, with full JIF information in the resource Journal Citation Reports (also includes Eigenfactor rankings and a five-year JIF).

Calculation: Uses a two-year period to divide the number of times articles were cited by the number of articles that were published.

Important points: A JIF can be easily skewed e.g. if a single article is very highly cited (a 2010 paper in Nature explains how this can happen).  Journal rankings evaluate the performance of a journal as a whole but say nothing about the impactfulness or quality of an individual article within the journal.

Finding JIFs

Journal Citation Reports ranks journals by the Journal Impact Factor score. It also provides the option to select 'Customize Indicators' and include: Impact Factor without Journal Self Cites, 5 Year Impact Factor, Eigenfactor/Normalized Eigenfactor, Cited Half-Life, Article Influence etc.

Guidance is available within the help pages of the Journal Citation Reports on Using journal citation reports wisely.

Watch the Web of Science training video below on how to find Journal Impact Factors using the resource Journal Citation Reports:

Watch the Web of Science Journal Profile Quick Tour video to see how the newly enhanced journal profile pages may help you better understand the content, regions, and institutions that make up a journal's impact factor.

Other resources

Scopus does not provide ranked lists of journals in a particular discipline but it has a good tool Compare Sources for selecting up to 10 journals and analysing a variety of citation parameters, including SJR (SCImago Journal Rank) and SNIP (Source Normalized Impact per Paper). See the Scopus help pages for Compare sources- About calculations for more information.

Scopus Compare sources

Watch the Scopus 'comparing sources' video below to find out how to do this:

SCImago logo

SCImago is a free website that uses Scopus data to provide ranked listings of journals, comparable to Journal Citation Reports.

Its primary focus is to rank journals by SJR (SCImago Journal Rank) but it also offers the following indicators for each journal: h-Index, Quartiles, Citations per document (2/3/4 years), Total Cites, Self-Cites, External Cites per Document, Cites per Document, International Collaboration, Citable Documents, Non-Citable Documents, Cites Documents, Uncited Documents.

The SCImago help pages contain information on how to find and rank journals, and also use the country search and country indicators.

SCImago provides ranked list of journals

Journal Metrics ranks journals by the CiteScore indicator

Journal Metrics is another site based on Scopus data.

It ranks journals by the CiteScore indicator, with options to rank journals by SNIP (Source Normalized Impact per Paper) and SJR (SCImago Journal Rank).

Note: As with other journal ranking indicators, to compare journals across disciplines requires a 'normalized' ranking. CiteScore provides a CiteScore Percentile which normalizes the raw CiteScore within its subject area. The scale runs from 100 (highest rank) down to 1 (lowest rank).

Important Points:

  • CiteScore is produced by a major publisher of journals (Elsevier) which some have criticized as "conflict of interest."
  • Because the CiteScore is based on raw citations counts, comparing CiteScores in different disciplines penalises journals in fields with naturally low citation numbers.
  • CiteScore may assign journals to more than one subject category. Additionally, the selected subject category for CiteScore in some cases has been either incorrect or questionable. (Elsevier is working to correct this)
  • If a journal has been assigned to more than one subject area, the CiteScore Percentile will be from the subject area in which the journal ranked the highest.
  • CiteScore includes front matter (editorials, news, letters to editors, etc.) in its calculations for how many documents are in each journal; consequently, journals with a lot of front matter, which is generally not cited, have a lower CiteScore than their 'Journal Impact Factor'.

Eigenfactor.org Journal Ranking tool

The Eigenfactor.org site includes a free to use Journal Ranking tool to search for a journal's Eigenfactor, Normalised Eigenfactor and Article Influence score. It is also possible to select an 'ISI Category' (Eigenfactor categories, see FAQ 5. for more information) and rank journal titles in that category.

Note: The citation data used at Eigenfactor.org comes from Journal Citation Reports. "Under an agreement with Thomson-Reuters, we are able to bring you the Eigenfactor metrics here at Eigenfactor.org free of charge. Scores will appear here annually, six months after they are released in the Thomson-Reuters Journal Citation Reports."

Eigenfactor, Normalised Eigenfactor and Article Influence scores are available in Journal Citation Reports:

Google Scholar Metrics to rank journals by their h-index

Google Scholar Metrics can be browsed to provide lists of journals by subject area, ranked by their h5-index (only available for 'English' publications). It also displays the h5-median for each included publication. Alternatively, it is possible to search on the journal title to find the h5-index of a specific journal.

Look at Google Scholar Metrics help pages to find out how to use it.

Note: Google Scholar Metrics currently cover articles published between 2011 and 2015, both inclusive. The metrics are based on citations from all articles that were indexed in Google Scholar in June 2016.