Different metrics have been developed to quantify the quality and impact of a journal. While these metrics are useful for identifying influential journals in a field, and demonstrating the prestige of published work, each has its strengths and weaknesses and should be used in combination with other factors when evaluating a journal.
Impact Factor, developed in the 1960s, remains the most commonly used measure of journal quality. In recent years, other metrics have been developed in an attempt to overcome some of the flaws of Impact Factor, and provide a more holistic assessment of journal quality. These metrics include: Eigenfactor, Article Influence, SCImago Journal Rank, Source Normalized Impact per Paper, Google Scholar Rankings, and Cabell's Directories.
For more information about the use of journal impact measures in evaluation, see the Leiden Manifesto for Research Metrics published as “Bibliometrics: The Leiden Manifesto for research metrics” in Nature 520, 429–431 (23 April 2015) doi:10.1038/520429a.
Eigenfactor and Article Influence scores are provided free of charge through Eigenfactor.org. Sponsored by the Bergstrom Lab at the University of Washington, The Eigenfactor project uses network methods to improve upon simple citation counts as a way of quantifying influence.
Eigenfactor is a weighted measure of influence. It takes into account multiple factors, such as:
Eigenfactor ends up being a measure of journal importance and value to it's field. The measurement can be used to compare journals from different subject fields.
Article Influence is the average influence of each of a journal's articles over the first 5 years after publication. It is a measure of the average influence per article for a journal, and it can be used to compare journals from different subject fields.
SCImago Journal Rank (SJR) and Source Normalized Impact per Paper (SNIP) are metrics that are available for free from SCImago Journal & Country Rank and CWTS Journal Indicators.
SCImago Journal Rank (SJR)
The SCImago Journal Rank is very similar to the Eigenfactor, but it uses information from Elsevier instead of Thomson-Reuters.
Source Normalized Impact per Paper (SNIP)
The Impact Factor (IF), is a trademark of Thomson-Reuters and is published in their Journal Citation Reports (JCR) database. Opponents of the measure argue that it is simplistic in it's measurements and does not take into consideration self-citations, the influence of the other journals in the field, and important impact of review articles for citation counts.
The IF measures:
The SDSU Library does not currently own access to Journal Citation Reports, but 2-yr IF for journals that are also indexed in Elsevier's Scopus database can be found freely at scimagojr.com.
Google Scholar Rankings: Calculates two measures for journal ranking. The h5-index is the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2015-2019 have at least h citations each. The h5-median for a publication is the median number of citations for the articles that make up its h5-index. More information
Cabell’s Directories: This database includes two measures, an evaluation of Journal Acceptance Difficulty and an Altmetric Report, an overview of where and how often articles are mentioned online. More information
