From a press release issued by Elsevier on Jan. 26, 2010:
Elsevier, publisher of scientific, technical and medical information products and services, today announced that its flagship product Scopus has successfully partnered with the Centre for Science and Technology Studies (CWTS) and the SCImago Research Group, endorsing two complementary journal metrics, SNIP and SJR. The metrics will be freely available online at www.journalmetrics.com, and integrated into Scopus, allowing researchers around the world to analyze journals within the abstract and citation database. The indicators will offer a greater currency and flexibility in journal performance measurement than any single-metric method currently available.
SNIP, which stands for Source Normalized Impact per Paper, measures a journal’s contextual citation impact and was developed by CWTS. It allows direct comparison of journals in different subject fields, by accounting for the frequency at which authors cite other papers, the speed of maturation of citation impact, and the extent to which the database covers the field’s literature.
SJR stands for SCImago Journal Rank, and was developed by the SCImago Research Group. It is a measure of the scientific prestige of scholarly sources: value of weighted citations per document. A journal transfers its own ‘prestige’, or status, to another through the act of citing it. In effect, this means that a citation from a source with a relatively high SJR is worth more than a citation from a source with a lower SJR.
Putting SNIP and SJR side by side and applying them to the breadth and depth of the Scopus database, which covers the greatest number of journal titles including local language titles from developed and emerging countries, the new offering represents the most inclusive bibliometric analytics available for journals. Their integration helps to meet the evolving needs of the scientific community by providing current, flexible, transparent data to empower users to build their own tailored journal ranking systems.
The journal metrics will be updated twice annually and made available to Scopus subscribers at http://www.scopus.com and to non-Scopus users at www.journalmetrics.com free of charge. Additional information on the SJR and SNIP indicators is available through the following recent publications:
- “Measuring contextual citation impact of scientific journals”, Henk Moed, Creator of SNIP (http://arxiv.org/abs/0911.2632)
- “The SJR indicator: A new indicator of journals’ scientific prestige”, BorjaGonzalez-Pereira, Vicente Guerrero-Bote, Felix Moya-Anegon (http://arxiv.org/abs/0912.4141)