Web of Science is the first and the main bibliographic database on a global scale. The platform's collection includes more than 196 million scientific articles and more than 34 thousand peer-reviewed journals. To measure the effectiveness and influence of publications and the professional activities of scientists, scientometric indicators have been introduced. We propose to familiarize with the main Web of Science metrics.
Web of Science basic scientometric metrics
The Web of Science database has its own metrics for calculating the productivity of scientific activity and the influence of scientific publications. The main ones are:
Journal Impact Factor (Journal Impact Factor)
An indicator to measure the prestige of a WoS peer-reviewed journal based on the average number of cited articles and their total number published in the journal in the two preceding years.
The formula for calculating:
impact factor for n year = number of citations of articles for two previous years / total number of given articles for the previous two years.
Citation Index
Citation Index is a general indicator that shows the scientific contribution of a particular scientist or journal to the academic community. It is used to evaluate the citation of articles, authors, and publications.
Citation Index is a general concept that covers several separate citation metrics. For Web of Science these are: h-index and Eigenfactor Score. Each of these indicators has its own specifics and formula for calculation.
Hirsch Index (H-index)
An index reflecting the productivity of the scientific work of a scientist or an academic journal. The index can characterize both the efficiency of a particular researcher or a group of scientists, and of an academic publication.
The formula for calculating the scientific productivity of a researcher:
scientist's h-index = h,
if h of his/her articles are cited at least h times.
Formula for calculating the scientific importance of a journal:
h-index of a journal = h,
if the journal has h articles, each of which has been cited at least h times.
Eigenfactor Score (ES)
ES is an indicator of journal prestige used in WoS. The metric was developed in 2006 by Carl Bergstromas an alternative to the classical impact factor. Eigenfactor Score is a kind of analog of Google's main algorithm, PageRank, which evaluates the importance of websites. Clarivate Analytics has taken as a basis an effective toolkit of Google's algorithm when ranking web resources.
The essence of the analytical tool Eigenfactor Score is that the prestige of a publication is evaluated relative to the number of citations of its articles by other influential journals.
The formula for calculating the ES metric:
ES of a journal = the number of citations received by the journal from other influential journals.
The total sum of ES values of all publications included in WoS equals 100 and is divided by all influential journals according to their prestige and depending on JCR citation rates for the current year based on citable scientific papers published in the previous five years.
Article Influence Score (AIS)
The Article Influence metric is used to measure the impact of specific articles. This index determines the importance of a journal based on the value of individual published articles, regardless of their number.
The formula for calculating the scientific impact of an article:
Eigenfactor Score of the journal / by the number of articles in the given journal, and it is necessary to normalize the score so that the average score is equal to 1.
Scientific journals with an AIS greater than 1 have an above average degree of influence. At the same time, if the AIS index is less than 1, the impact score of articles of a particular publication is below average.
New Normalized Eigenfactor (nEF) Score
The new Web of Science metric, Normalized Eigenfactor Score, is a refinement of the previously introduced Eigenfactor Score index. The latter metric has a total score for all journals of 100. Due to the large number of publications we have to work with small decimal numbers, this leads to the fact that the vast majority of journals have very low scores. To improve and enhance the interpretation of this indicator, a new index, nEF, was introduced.
The new modification has the following formula for calculation:
Each Eigenfactor Score * 1/100, the resulting number should be multiplied by the total number of journals in Journal Citation Reports (JCR).
Thus, the journal score will be a multiple of the average score in JCR equal to 1.
The new modification is more understandable in comparison with the classical Eigenfactor Score and corresponds to the interpretation of the AIS indicator.
In Web of Science it is possible to find the necessary scientometric indicators by searching by journal or article title and selecting the desired metrics. Web of Science tools automatically calculate all indices. The above indices help to evaluate and compare scientific journals, articles and authors' productivity, as well as to identify trends in scientific research.
What are the quartile and percentile of a journal in Web of Science?
The statistical metrics quartile and percentile are also used to calculate the impact of a journal in the WoS database. These metrics help researchers and scientific organizations/institutions to determine how prestigious a journal is in a particular field, as well as to compare scientific publications among themselves.
Quartile - an indicator that divides all publications into 4 groups depending on the impact factor and other citation indicator. Q1 (first quartile) includes the most influential and respected publications in the academic society. Q4 (fourth quartile) is a group of scientific journals with low Impact Factor.
Percentile - a relative indicator that clearly shows the position of a journal among similar journals in a particular field. The position of a journal in relation to all publications in the same category is measured in percentages - from 1% to 99%, where 99% is considered the maximum indicator.
These metrics are used for comparative analysis of journals when selecting a journal for publication. Quartiles and percentiles clearly show the influence and prestige of a publication.
Experts of Scientific Publications have been providing scientific consulting services to scientists from all over the world for more than 8 years. We know all the subtleties of the scientific publishing process in the international databases Web of Science and Scopus. If you need to improve your scientific metrics or increase Hirsch index (h-index), leave a request on the website and we will contact you within a working day.
