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Bibliometrics and Altmetrics

Journal Impact Factor

Journal Impact Factor is frequently used as a proxy for the importance of a journal to its field. Journal Citation Reports (JCR), Eigenfactor and SCImago Journal & Country Rank (SJR), and Scopus are tools for finding the impact of a journal or groups of journals.

More specifically, impact factor is “a measure of the frequency with which the ‘average article’ in a journal has been cited in a particular year or period” (Morrison 12).  The more cited a journal, the more prestige for that journal.  When using impact factors, make sure to compare the ranking of a journal to other journals in the same discipline.

Below is a calculation of the journal Nature's impact factor for 2014. 

- Wikipedia (Impact Factor entry)

Journal Citation Reports (JCR)

The 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. [Garfield, 2005] Journal impact factor applies only to a journal or groups of journals, but not to individual articles or individual researchers.

The impact factor of a journal in a particular year is the number of citations received in the current year to articles published in the two preceding years divided by the number of articles published in the same two years. For example, Pediatrics has a 2006 impact factor of 5.012, which means that on average each of its 2004 and 2005 articles was cited 5.012 times in 2006.

Note that Eigenfactor Metrics (Eigenfactor score  and Article Influence score) are available in JCR for the years 2007 and later.

How to find the Journal Impact Factor by individual journal title or by subject groupings:

Subject:

  1. Go to JCR.
  2. Select a JCR edition year from dropdown list. (leave View a group of journals by Subject Category).
  3. Click Submit button.
  4. Select one or more subject categories (hold down control <ctrl> key while clicking subjects).
  5. Select Journal or Category data sorts. Under View Journal Data, select Impact Factor.
  6. Click Submit button.

Individual Journal Title:

  1. Go to JCR.
  2. Select a JCR edition year from dropdown list.
  3. Click radio button to the left of ‘Search for a specific journal’.
  4. Click Submit button.
  5. Enter journal information by complete title, ISSN, abbreviated journal title, or title word.
  6. Click Search button.

In results table click individual journal title for complete information (e.g., explanations of impact factor, immediacy index, citing and cited half-life)

For more details see:

Eigenfactor

Eigenfactor ranks and maps scientific knowledge:

  • Ranks journals similar to Google ranking of websites. It uses the structure of the entire network (instead of purely local citation information) to evaluate the importance of each journal.  Journals are rated according to the number of incoming citations, with citations from highly-ranked journals weighted to make a larger contribution to the eigenfactor than those from poorly-ranked journals.
  • Eigenfactor Metrics consists of the Eigenfactor score  and the Article Influence score.
    • Eigenfactor score: a measure of the overall value provided by all of the articles published in a given journal in a year. 
    • Article Influence score: a measure of a journal's prestige based on per article citations and comparable to Impact Factor.
  • Measures journal price as well as citation influence. The Cost-Effectiveness Search orders journals by a measure of the value of the dollar they provide.
  • Ranks scholarly journals as well as newspapers, theses, popular magazines, etc.
  • Adjusts for citation differences across disciplines, allowing for better comparison across research areas.
  • Calculations are based on the citations received over a 5-year period vs. 2 years in JCR.
  • Available free of charge on the web. [eigenfactor.org, 2009]

How to find the Eigenfactor:

  1. Go to eigenfactor.org
  2. Search for a single journal name or choose a subject category.
  3. Select a year.
  4. Click Search.

Note: advanced search (searches by Thomson JCR subject categories, publisher, and other fields) is also available.

SCImago Journal & Country Rank

SCImago Journal & Country Rank (SJR) is free source that includes the journals and country scientific indicators developed from Elsevier's Scopus database.  It ranks journals and compares journal citation among countries.   Journals are assigned to major thematic categories as well as to specific subject categories according to Scopus Classification. 

The SJR (SCImago Journal Rank) indicator expresses the average number of weighted citations received in the selected year by the documents published in the selected journal in the three previous years, --i.e. weighted citations received in year X to documents published in the journal in years X-1, X-2 and X-3.For more information, see Description of SCImago Journal Rank Indicator.

How to find journal rankings in SJR:

  1. Go to SJR and click on Journal Rankings.
  2. Select Subject Area, e.g., Nursing.
  3. Select Subject Category, e.g., Maternity and Midwifery.
  4. Select other categories as needed and click Refresh.

Scopus database - including the SJR, SNIP and CiteScore

Explanation of SJR, SNIP, and CiteScore

SJR, or SCImago Journal Ranking, is based on the Journal Impact Factor (JIF) citation formula, but uses a 5-year citation count and applies an algorithm based on Google's to calculate their index.

SNIP is based on SJR, but is 'flattened' or normalized to more easily allow for direct comparison between separate disciplines.

CiteScore is a newer metric uses JIF's citation formula, but uses a 3-year citation count, and is more directly comparable with JIF, due to the similar methodology.

SJR, SNIP, and CiteScore are based on citation records in Scopus.

Availability

SJR, SNIP, and CiteScore are all also available through Scopus (click on "Sources" from the home page), but subject rankings are only available based on CiteScore. (More information about disciplines is available in Journal Rankings.) 

Scopus also allows for direct graphical comparisons of journals, as demonstrated to the right. This can be found in any individual journal's record in Scopus by clicking on "Compare sources" in the upper-right corner.

SJR, SNIP, and CiteScore are also available through journalmetrics.com. Subject rankings are available based on SJR, SNIP and CiteScore here.

SJR is also available through SCImago's website, including journal rankings.

 

 

 

This section comes from the Scholarly Research Impact Metrics Library Guide published by the Library at American University.

Google Scholar and H5-index

Explanation of H5-index and H5-median

The H5-index is created by Google Scholar, and is similar to the h-index explained in Author-level Metrics.

H5-index "It is the largest number h such that h articles published in [the past 5 years] have at least h citations each". Thus, an H5-index of 60 means that that journal has published 60 articles in the previous 5 years that have 60 or more citations each.

H5-median is based on H5-index, but instead measures was the median (or middle) value of citations is for the h number of citations. A journal with an H5-index of 60 and H5-median of 75 means that, of though 60 articles with 60 or more citations, the median of those citation values is 75.

Below is a screenshot of the top journals for Library & Information Science ranked by the H5-index.

Availability

Both the H5-index and H5-median are available in Google Scholar Metrics. Journals can be browsed by discipline (more information about disciplines is available in Journal Rankings) or searched by keyword.

Limitation

Google Scholar Metrics will only display the top 20 journals for each subject category. Additionally, there is no historical data.

 

This section comes from the Scholarly Research Impact Metrics Library Guide published by the Library at American University.

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