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Publication Metrics

This is a guide to the various metrics used to measure research impact.

What Are Journal Metrics?

Journal-level metrics attempt to quantify a journal's impact by analyzing the citations arising from the articles it publishes.

Advantages: Journal metrics can give a sense of which journals are popular and/or respected within a specific field.

Disadvantages: These metrics effectively average the impact of a journal's articles and authors, so they hide variations among articles and authors. Journal metrics also are not generalizable across disciplines.

Beware of Bogus Impact Factors

In a recent post on the Scholarly Open Access blog, Jeffrey Beall describes the recent proliferation of potentially bogus impact factor companies. It is important to evaluate the methodoloies used by organizations that produce journal rankings. Some rankings include a narrow lists of titles. Others have been known to award high impact factors to journals -- for a fee.

JCR Impact Factors

The Journal Citation Reports (JCR) Impact Factor is calculated by dividing the number of citations in a year by the total number of articles published in the two previous years. For example, an Impact Factor of 1.0 means that, on average, the articles published in a given journal one or two year ago have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times.



The Eigenfactor, like the Impact Factor, starts with the citation data from Journal Citation Reports but has a more complicated algorithm. Journals are considered to be more influential if they are cited often by other influential journals. For example, citations from Nature or Cell are valued more highly than citations from journals with a narrower readership. Eigenfactor scores are also adjusted for differences in citation patterns across disciplines. They rely on data from five years, as compared to two for the Impact Factor.

Eigenfactor scores are scaled so that the sum of the Eigenfactor scores of all journals listed in Journal Citation Reports (JCR) is 100. In 2012, the journal Nature had the highest Eigenfactor score, with a score of 1.56539. In 2020, Nature fell to #4 with a score of 1.21714. PloS One had the highest Eigenfactor with a score of 1.38933.


PubsHub includes Impact Factors and Eigenfactors as well as information to help decide where to publish. It includes:

  • Rejection rate
  • Time to acceptance 
  • Time to publication
  • Instructions for Authors


The SCImago Journal & Country Rank is a portal that includes the journals and country scientific indicators developed from the information contained in Elevier's Scopus database.


Google Scholar Metrics

Google Scholar Metrics is available by clicking "Metrics" from the Google Scholar homepage. It offers a list of the top journals in specific fields according to their h-index and h5-median values, based on the citation information in Google Scholar.