Bibliometrics & Responsible Research Evaluation: Journal Impact
Use of Journal Metrics
Journal metrics are not appropriate for evaluating an individual article or researcher as they are a journal level indicator.
These metrics can be a broad indicator or guide to the general visibility of a journal. Journal metrics can also be used as a collection development tool for libraries when evaluating which journals to purchase or subscribe to.
Journal Impact Metrics
- Journal Impact Factor (JIF)Uses Web of Science/Clarivate Analytics (formerly Thomson Reuters) citation data. The journal Impact Factor is the average number of times articles from the journal published in the past two years have been cited in the Journal Citation Reports (JCR) year.
- CiteScoreUses Elsevier citation data from Scopus and is based on a four year citation window.
- Article InfluenceUses Web of Science/Clarivate Analytics citation data. In Journal Citation Reports or at http://www.eigenfactor.org. The Article Influence Score calculates and measures the relative importance of the journal on a per-article basis.
- EigenfactorUses Web of Science/Clarivate Analytics citation data. In Journal Citation Reports or at http://www.eigenfactor.org. The Eigenfactor Score measures the number of times articles from the journal published in the past five years have been cited in the JCR year.
- Scimago Journal and Country Rank (SJR)Uses Elsevier (Scopus) citation data. SJR is a prestige metric based on the idea that ‘all citations are not created equal’. With SJR, the subject field, quality and reputation of the journal has a direct effect on the value of a citation.
- Source Normalized Impact per Paper (SNIP)Uses Elsevier (Scopus) citation data. 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.
- Google Scholar MetricsUses Google Scholar publication information to rank journals by their h-5 index.
The average citation level of a journal is an extremely limited indicator, and is not a replacement for expert, qualitative assessment of the journal. The distribution of citations is typically skewed, therefore using the mean is problematic. Many articles published in "high impact" journals receive very few or indeed no citations at all. Many factors can influence citation rates such as language, journal history, publication schedule, and subject specialty and scope.
Other factors which can affect a journal's ranking or metrics include:
- article type(s)
- changes in journal format
- title changes
- cited-only journals (i.e. whereby references from a journal (including self-citations) are not included in the dataset)
Many of the journals in Web of Science and Scopus are English-language from North America, Western Europe and Australia. Irish journals in many research areas can be underrepresented.
Review journals and original research journals are treated the same even though the citation patterns of these types of articles differ.