Elsevier have announced the release of the 2013 Journal Metrics based on Scopus data.
The metrics provide methods for assessing the citation impact a journal makes and are all available for free download at http://www.journalmetrics.com.
The impact metrics are based on methodologies developed by external bibliometricians and use Scopus as the data source. Scopus is the largest citation database of peer-reviewed literature and features tools to track, analyse and visualize research output.
Source Normalized Impact per Paper (SNIP)
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. As a field-normalized metric SNIP provides the ability to benchmark and compare journals from different subject areas. A component of the SNIP calculation is the raw Impact per Publication (IPP) which measures the ratio of citations per article published in the journal.
The SNIP was developed by Leiden University’s Centre for Science & Technology Studies (CWTS).
SCImago Journal Rank (SJR)
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 have a direct effect on the value of a citation. It is a size-independent indicator and it ranks journals by their ‘average prestige per article’ and can be used for journal comparisons in the scientific evaluation process.
The SJR was developed by the SCImago research group in Spain.
More information, including a downloadable file with all journal metrics, can be found on http://www.journalmetrics.com.