In previous blogs of the “Scientific Publications” Company, we mentioned that citations are one of the key metrics of the scientometric world. There are a large number of special indicators and their calculation methodologies, which are based on the number of citations. They are calculated for authors, individual scientific works, universities, entire countries and, of course, scientific journals. We suggest you considering the peculiarities of scientometric indicators of publications within the Scopus and Web of Science databases.
Scopus journals and citations calculation
The main metrics at the level of a scientific publication include SNIP, SJR and CiteScore:
- SNIP is a normalized journal citation index. In order to calculate it, the citations number is compared to the scientific articles number of the publication for 3 years. Also, the calculations take into account the normalized indicator, which differs depending on the subject area. It is because of that SNIP is considered an integrated metric that does not depend on the field of research. The indicator is calculated for journals from the Scopus database in cooperation with representatives of Leiden University. When calculating, the following is calculated: P is the number of articles; IRR is a metric without taking into account the normalized indicator; % self cit. is the percentage of the publication self-citation.
- SJR - SCIMago Journal Rank, is a metric calculated in partnership with the SCIMago laboratory. The indicator is very difficult to calculate and is based on the citations number, the authority of each of them and whether they are related to the subject area. For example, one citation in a ranked journal is ranked higher than a similar one in a lesser-known journal.
- CiteScore is a metric developed exclusively by Elsevier specialists. It is calculated as the ratio of the citations average number to articles over the past 4 years. In addition to the main CiteScore metric, there are a number of derivatives: CiteScore Tracker is a monthly indicator; CiteScore Percentile is a percentile, a relative index of the journal’s ranting in the subject area; CiteScore Quartile is a quartile, influence level; CiteScore Rank and Rank Out Of is an absolute rank in the subject area; Citations is a number of citations; Documents is number of documents.
Information about these metrics is posted on the journal page in the Scopus database:
Web of Science citations and metrics calculation
The Web of Science database has a slightly different specifics of scientometric indicators calculation. Of course, some conclusions about the publication that is indexed in this database can be made already at the level of its inclusion in one or another citation index. The metrics calculation often depends on this. For example, the impact factor is calculated exclusively for two citation indexes: Science Citation Index Expanded (SCIE) and Social Sciences Citation Index (SSCI).
So, pay attention to the following log indicators:
- Journal Impact Factor is determined by the ratio of citations to the articles number in 1 (operational), 2 (classical), 5 or 10 years. Many derivatives are defined on the basis of this metric: Quartile is quartile as an indicator of publication rank; Percentile is percentile as a relative percentage indicator of the publication’s rank; Rank is an absolute indicator of the journal's influence in a certain subject area.
- Journal Citation Indicator is a recently introduced Web of Science metric that minimizes some of the impact factor shortcomings (in particular, regarding the database materials coverage). The metric is calculated as the ratio of the citations number to the articles number taking into account the normalized indicator for the subject area.
Information about these indicators should be sought on the Journal Citation Reports platform.
What is a journal quartile and its percentile?
It was mentioned earlier that quartiles and percentiles are calculated for both Scopus and Web of Science journals. They are often the most popular when evaluating scientific publications and are used in regulatory documents of many countries around the world.
However, it should be noted that despite the name similarity, these metrics differ depending on the database, because, as we defined earlier, excellent scientometric indicators are calculated within their framework. Let’s consider in more detail what quartile and percentile are:
- Quartil is an indicator that ranks publications into 4 groups, where Q1 is the most ranked; Q4 is less ranked. In order to do this, all journals in the subject area are divided into four approximately equal categories.
- Percentile is a relative indicator by subject area from 1 to 99, where 99% is considered the highest. There is no 100% percentile. The indicator of 99% indicates that the publication is in the top 1% in the subject area.
It should be noted that the same publication can have several quartile and percentile indicators, not only due to the specifics of the databases, but also depending on the knowledge category.
In order to search Scopus journals by quartile, you need to go to the “Sources” tab and limit the search to the required quartile:
Percentile indicators for each scientific publication are placed on the journal page in the “CiteScore rank” and “CiteScore rank & trend” columns:
In Web of Science all information about quartile and percentile indicators is located on the Journal Citation Reports.
You can also find the quartile indicators on the Scimago Journal & Country Rank resource (based on the Scopus database). Previously, this Scopus metric was placed exclusively there because it was calculated by SJR. Searching for a journal is intuitively simple: you should enter the title or ISSN and select the required publication. All detailed information about scientometric indicators will be posted on its page.
The “Scientific Publications” Company has been an absolute leader in the field of scientific and publishing consulting for more than 6 years that indicates the absolute professionalism of our team. We deeply understand all the details of working with editions of the largest scientometric databases Scopus and Web of Science. Choose the “Publications in Scopus” or “Publications in Web of Science” service, and our specialists will provide you with full support for the scientific work, with special emphasis on the comprehensive analysis of the journal scientometric indicators in which the scientific work is planned to be published.
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We will remind you that the material “How to write a scientific article in the field of medicine?” was recently released
