Journal Metrics are used to measure the performance or impact of individual journal titles. They vary from the basic premise of counting the number of citations made to articles in specific journals, to offering different perspectives on the scholarly publishing landscape by using different methodologies and data sources.
The Metrics Toolkit is a free resource which has been developed by an international group of information professionals to help researchers and evaluators of research to understand and use citations, web metrics, and altmetrics responsibly in claims of research impact. The Toolkit provides information about research metrics (both traditional and non-traditional) across disciplines, including how each metric is calculated. There are also examples of how to use metrics in grant applications, CVs, and portfolios.
Journal Impact Factor* and Journal Citescore** are metrics that measure ratios of citations that papers in a given journal have received in one year, to those received in previous years.
A journal's Impact Factor or Citescore is often publicized on its homepage, and there are tools available to benchmark metrics against one another. Free services to lookup Citescore and other journal metrics from the Scopus database are Scopus Journal Metrics and CWTS Journal Indicators. All document types are included in the CiteScire calculation (except in-press items) but it is not field-weighted so it is not appropriate for comparison between different subject areas for which SJR and SNIP values (as below) should be used. Journal Impact Factor is not freely available - apart from when advertised on individual homepages - but available via subscription to Journal Citation Reports.
A guidance note on bibliometrics is available for staff and researchers from the University Research Office intranet page.
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** Copyright © 2017 Elsevier B.V. All rights reserved
SJR is a prestige metric based on the methodology inspired by the Google PageRank algorithm and the idea that not all citations are the same. With SJR, the subject field, quality and reputation of the journal have a direct effect on the value of a citation and the impact that journal makes.
This metric is based on citation data from the Scopus database. It is freely obtainable on the Web from the Scopus Journal Metrics website and Journal Rankings by Subject categories are also available.
Discipline plays an important factor in addressing the balance of relatively high and low citation counts. Source Normalized Impact per Paper measures contextual citation impact by weighting citations based on the total number of citations in a subject field. It aims to allow direct comparison of sources in different subject fields.
Detailed information about the calculation of this metric is available in an overview page and in open access papers reporting the original development of the metric and some further refinements of it.