SCImago Journal Rank
Encyclopedia
SCImago Journal Rank is a measure of scientific influence of scholarly journal
s that accounts for both the number of citation
s received by a journal and the importance or prestige of the journals where such citations come from. The SJR indicator is a variant of the eigenvector centrality measure
used in network theory. Such measures establish the importance of a node in a network based on the principle that connections to high-scoring nodes contribute more to the score of the node. The SJR indicator, which is inspired by the PageRank
algorithm, has been developed to be used in extremely large and heterogeneous journal citation networks. It is a size-independent indicator and its values order journals by their "average prestige per article" and can be used for journal comparisons in science evaluation processes.
The SJR indicator is an open access journal metric which uses an algorithm similar to PageRank
and provides an alternative to the impact factor
(IF), which is based on data from the Science Citation Index
. Average citations per document in a 2 year period, abbreviated as Cites per Doc. (2y), is another index that measures the scientific impact of an average article published in the journal. It is computed using the same formula that journal impact factor
(Thomson Reuters
).
that distributes prestige values among the journals until a steady-state solution is reached. The SJR algorithm begins by setting an identical amount of prestige to each journal, then using an iterative procedure, this prestige is redistributed in a process where journals transfer their achieved prestige to each other through citations. The process ends up when the difference between journal prestige values in consecutive iterations do not reach a minimum threshold value any more. The process is developed in two phases, (a) the computation of Prestige SJR (PSJR) for each journal: a size-dependent measure that reflects the whole journal prestige, and (b) the normalization of this measure to achieve a size-independent measure of prestige, the SJR indicator.
Academic journal
An academic journal is a peer-reviewed periodical in which scholarship relating to a particular academic discipline is published. Academic journals serve as forums for the introduction and presentation for scrutiny of new research, and the critique of existing research...
s that accounts for both the number of citation
Citation
Broadly, a citation is a reference to a published or unpublished source . More precisely, a citation is an abbreviated alphanumeric expression Broadly, a citation is a reference to a published or unpublished source (not always the original source). More precisely, a citation is an abbreviated...
s received by a journal and the importance or prestige of the journals where such citations come from. The SJR indicator is a variant of the eigenvector centrality measure
Centrality
Within graph theory and network analysis, there are various measures of the centrality of a vertex within a graph that determine the relative importance of a vertex within the graph...
used in network theory. Such measures establish the importance of a node in a network based on the principle that connections to high-scoring nodes contribute more to the score of the node. The SJR indicator, which is inspired by the PageRank
PageRank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...
algorithm, has been developed to be used in extremely large and heterogeneous journal citation networks. It is a size-independent indicator and its values order journals by their "average prestige per article" and can be used for journal comparisons in science evaluation processes.
The SJR indicator is an open access journal metric which uses an algorithm similar to PageRank
PageRank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...
and provides an alternative to the impact factor
Impact factor
The impact factor, often abbreviated IF, is a measure reflecting the average number of citations to articles published in science and social science journals. It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed...
(IF), which is based on data from the Science Citation Index
Science Citation Index
The Science Citation Index is a citation index originally produced by the Institute for Scientific Information and created by Eugene Garfield in 1960, which is now owned by Thomson Reuters. The larger version covers more than 6,500 notable and significant journals, across 150 disciplines, from ...
. Average citations per document in a 2 year period, abbreviated as Cites per Doc. (2y), is another index that measures the scientific impact of an average article published in the journal. It is computed using the same formula that journal impact factor
Impact factor
The impact factor, often abbreviated IF, is a measure reflecting the average number of citations to articles published in science and social science journals. It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed...
(Thomson Reuters
Thomson Reuters
Thomson Reuters Corporation is a provider of information for the world's businesses and professionals and is created by the Thomson Corporation's purchase of Reuters Group on 17 April 2008. Thomson Reuters is headquartered at 3 Times Square, New York City, USA...
).
Rationale
If scientific impact is considered related to the number of endorsements, in the form of citations, a journal receives, then prestige can be understood as a combination of the number of endorsements and the prestige or importance of the journals issuing them. The SJR indicator assigns different values to citations depending on the importance of the journals where they come from. This way, citations coming from highly important journals will be more valuable and hence will provide more prestige to the journals receiving them.Computation
The SJR indicator computation is carried out using an iterative algorithmAlgorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
that distributes prestige values among the journals until a steady-state solution is reached. The SJR algorithm begins by setting an identical amount of prestige to each journal, then using an iterative procedure, this prestige is redistributed in a process where journals transfer their achieved prestige to each other through citations. The process ends up when the difference between journal prestige values in consecutive iterations do not reach a minimum threshold value any more. The process is developed in two phases, (a) the computation of Prestige SJR (PSJR) for each journal: a size-dependent measure that reflects the whole journal prestige, and (b) the normalization of this measure to achieve a size-independent measure of prestige, the SJR indicator.