Journal Level Metrics
Journal level metrics are used to indicate the impact of scholarly journals – not articles or authors. Researchers often use the metrics to identify significant journals in a field, and inform their publishing strategies to maximize the reach of their works.
The metrics are only available for the journals indexed in the specific citation databases. For example, only journals indexed by Web of Science Core Collection (SCIE, SSCI, AHCI, ESCI) will have journal impact factors.
Journal Impact Factor (JIF)
Journal Impact Factor (JIF) can essentially be defined as the annual average number of citations to papers in any given journal in the two preceding years:
JIF is updated annually and varies every year.
It is only available for the journals indexed in Web of Science Core Collection, including:
Web of Science Core Collection is curated by an expert team of in-house editors, which, as the publisher explains, includes only journals demonstrating high levels of editorial rigor and best practice.
Journal Impact Factor Quartile
The Journal Impact Factor quartile is the quotient of a journal’s rank in category (X) and the total number of journals in the category (Y), so that (X / Y) = Percentile Rank Z.
Note: Journals may appear in multiple Web of Science categories, and are at different quartiles among the categories.
Use and limitations
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Access
Journal Citation Reports (JCR): http://find.lib.hku.hk/record=alma991019172539703414
References
CiteScore
CiteScore is based on the number of citations to documents (articles, reviews, conference papers, book chapters, and data papers) by a journal over four years, divided by the number of the same document types indexed in Scopus and published in those same four years:
It is calculated annually and available on Scopus. Scopus contents are reviewed and selected by an independent Content Selection and Advisory Board (CSAB), an international group of researchers with journal editor experience, based on their selection criteria.
Use and limitations
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Access
Scopus: http://find.lib.hku.hk/record=alma991012748039703414
References
TOP Factor
TOP Factor (Transparency and Openness Promotion Factor) is a metric that reports the steps that a journal is taking to implement open science practices, practices that are based on the core principles of the scientific community. It is an alternative way to assess journal qualities, aiming to improve over traditional metrics that measure citations. Journals are scored based on ten different criteria, e.g., availability of data and policies on preregistration. The criteria can be found here: https://www.cos.io/initiatives/top-guidelines.
Use and limitations
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Access
TOP Factor: https://topfactor.org/
References
Other metrics are also provided by various databases.
Here are some examples:
Journal Citation Reports (Web of Science)
Access: http://find.lib.hku.hk/record=HKU_IZ61507704370003414
Indicators | Definition | Guide |
5-Year Journal Impact Factor | The average number of times articles from the journal published in the past 5 years have been cited in the JCR (Journal Citation Reports) year | https://incites.help.clarivate.com/Content/Indicators-Handbook/ih-5-year-jif.htm |
Eigenfactor | Based on 1.) the number of times articles from the journal published in the past five years have been cited in the JCR year, and 2.) which journals have contributed these citations so that highly cited journals will influence the network more than lesser cited journals |
https://incites.help.clarivate.com/Content/Indicators-Handbook/ih-eigenfactor.htm |
Journal Citation Indicator (JCI) | A field-normalized metric representing the average category-normalized citation impact for papers published in the prior three-year period. | https://clarivate.com/blog/introducing-the-journal-citation-indicator-a-new-field-normalized-measurement-of-journal-citation-impact/ |
Scopus
Access: http://find.lib.hku.hk/record=HKU_IZ61518360550003414
Indicators | Definition | Guide |
SCImago Journal Rank (SJR) | The average number of weighted citations received in the selected year by the documents published in the selected journal in the three previous years | https://www.scimagojr.com/help.php#understand_journals |
Source Normalized Impact per Paper (SNIP) | Measuring contextual citation impact by weighting citations based on the total number of citations in a subject field | https://blog.scopus.com/posts/journal-metrics-in-scopus-source-normalized-impact-per-paper-snip |