Research Impact

CiteScore: Metric in Scopus most closely related to Impact Factor. Citations received by all articles published in the last 4 complete years are divided by the number of articles published in the last 4 years.

SCImago Journal Rank (SJR): Measures the scholarly influence of a journal by accounting for the number of citations as well as the prestige of the citing journals. SJR is based on the eigenvector centrality measure used in network theory. It is a size-independent measure that ranks journals based on their average prestige per article. 

Source Normalized Impact per Paper (SNIP): Measures the contextual citation impact of a journal by weighting the citations based on the total number of citations in a discipline. This method normalized for differences in citation practices between disciplines, so that a single citation is given greater value where citations are less frequent in that field. 

Scopus also provides metrics for number of citations, number of documents, percentage of documents cited, and CiteScore rank (how the CiteScore for the journal compares to other journals in the same field). Explore all the metrics by searching the Sources list in Scopus.

The Impact Factor is a long-standing metric commonly used to evaluate journals. It is an equation calculating the average citation frequency for a given journal over a given period of time. It is a ratio of citations to citable items. Generally speaking, the higher the number, the higher the quality and prestige of the journal, although the impact factor is most useful when evaluating journals within the same discipline. 

A/B = Impact Factor
A = cites by all indexed articles in a given year to articles published in a specific journal in the two preceding years.
B = total number of articles published by that journal in that time period.

The journal Impact Factor was invented in the 1960s by Eugene Garfield and was intended as a tool to help librarians make selection decisions and authors identify publishing venues. Today, the Impact Factor is a proprietary calculation that is available only through Thompson Reuters Journal Citation Reports. 

Pros

• Vetted, established metrics for measuring journal impact within a discipline
• Designed to eliminate bias based on journal size and frequency

Cons

• Individual articles makes an uneven contribution to overall metric.
• These metrics do not account for certain things, things like context (positive or negative citation) and intentionality (self-citation).
• The metrics are proprietary to and bound by the contents of their respective databases: Scopus for CiteScore and the Thomson Reuters database for Impact Factor. 
• Citations, on which the Impact Factor is based, count for < 1% of an article's overall use. 

Eigenfactor: A measure of a journal's overall importance to the scientific community based on the origin of incoming citations over a period of time; citations from highly ranked journals are weighed more heavily. (Hosted by the University of Washington; built on Thomson Reuters bibliographic data.)

• Eigenfactor Journal Ranking

Journal Metrics: Publicly accessible metrics for journal evaluation that offer three alternative views of true citation impact of a journal. (Provided by Elsevier; built on Scopus bibliographic data.)

• SCImago Journal Rank (SJR): Defined above.
• Source Normalized Impact per Paper (SNIP): Defined above.
• Impact per Paper (IPP): Measures the ratio of citations to citable items for a given journal over a given period of time. IPP is the most direct correlate to the Impact Factor, but it calculates this ration over three years rather than two and it includes only peer-reviewed scholarly papers in both the numerator and the denominator. IPP is the foundational metric for the SNIP. 

Article-level metrics provide a more accurate picture of an article's impact than the impact of the journal it is published in.

Article-level metrics include:

• Citation count (Available through many databases and often on the publisher website.)
• Field-weighted citation impact (Calculated ratio in Scopus of the article's citations compared to the average number of citations received by all similar articles over a three-year window. A value greater than 1 means the article is cited greater than average.)
• Citation percentile (Scopus percentile comparing an article's citation count to the number of citations received by documents of the same type, published around the same time, in the same field.)
• View and/or download count (Number of times an article has been viewed and/or downloaded. Available in Scopus and often on the publisher website.)
• Altmetric score (Compilation of alternative metrics such as media mentions and citations in policy documents. Available through Altmetric Explorer for Institutions and on publisher websites which use Altmetric badges.)
• PlumX metrics (Compilation of alternative metrics such as social media mentions and Mendeley readers. Available in Scopus and on publisher websites which use PlumX.)