Understanding the SCI and the Impact Factor
What is SCI?
The Science Citation Index (now the Science Citation Index Expanded, or SCIE) is one of the core databases included in the products Web of Knowledge and Web of Science, owned by Clarivate. This was formerly owned by Thomson Reuters, who were acquired by Clarivate in 2016.
In fact, Web of Science comprises a number of database resources, and the journals covered are subject to an evaluation process before inclusion. You can learn more about Web of Science by visiting the Clarivate website.
Publishers wishing to get their journals evaluated need to submit a proposal to a committee which oversees the ‘Web of Science Core Collection Journal Selection Process.’ The evaluation takes into consideration a number of criteria, and it is notable that these include not just an analysis of the citations to its content, but also factors such as the editorial process and adherence to good publishing practices. For example, this is often considered in relation to the peer review process, the timeliness of publication, and also the scope and international provenance of the journal.
What are the Evaluation Criteria?
Want to learn more about the criteria? You can learn more from Clarivate about the evaluation and curation of their data here, which they are confident makes Web of Science the world’s most trusted publisher-independent global citation database.
The article linked above shows why a journal will expect you to follow certain processes and adhere to deadlines during the submission process, and also will expect you to format your article to meet their formatting criteria. They make these stipulations so that they themselves can adhere to the standards required by the selection and inclusion process.
Journal Impact Factor
Statistics from Thomson Reuters showed that about 3500 journals are evaluated annually, and around 10% will be selected for inclusion. Once included, the ‘citation impact’ is published annually, in the summer, detailing the ‘Journal Impact Factor’ of those journals included.
The first ‘impact factors’ were published in 1975. Impact factors are published in an annual report known as the Journal Citation Reports (JCR), which is part of the Web of Science portfolio.
You need to have a subscription to access the Web of Science content and reports, but many institutions will have this. Talk to your librarian or departmental colleagues if you are unsure if you have access or how to use the products.
What is an Impact Factor?
The impact factor is a measure of the citations published within a given journal over a fixed time period. Specifically, it reflects the average number of citations for each paper published in a journal during the two preceding years. So:
- Where A = total citations in 2014
- B = 2014 citations to articles published in 2012-13 (this is a subset of A)
- C = number of articles published in 2012-13
- D = B/C = 2014 impact factor
It should be noted that new journals need to wait 2 years before they can be evaluated and given an impact factor, though there are some occasional exceptions to this, where impact factors based on partial data have been given.
There can be factors that influence the impact factor, such as the publication of review articles. This has a more significant impact because review articles, naturally, tend to include higher numbers of citations to earlier literature.
Self-citation can also influence the metrics, but it should be noted that the Journal Selection Process takes this into consideration, and artificially high levels of deliberate self-citation will affect the selection process.
Does the Journal need to be in English?
In short: no, a journal does not need to be in English. However, as the majority of leading scientific journals are published in English, there is an emphasis on English-language publications. There are examples of journals which only publish abstracts and references in English with the main text in another language, but these are in the minority. All journals need to carry their references and bibliographic information in the ‘Roman’ alphabet.
In fact, there is more flexibility within social sciences, where local-language publications are important because they reflect the context of the regional or linguistic areas of study.
It is interesting to note that Web of Science is actively encouraging further submission of regional journals for evaluation, to complement the international coverage that it has traditionally included.
Although it was published a few years ago, The Globalization of Web of Science, 2005-2010, by James Testa, contains more detail on how the coverage of regional journals has increased over time, and this trend is expected to continue. You can read the full essay here.
Want to know more about SCI and the Impact Factor?
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