Bibliometrics is a scientific discipline focused on the quantitative analysis of documents produced within the framework of scholarly communication. The fundamental bibliometric methods include publication and citation analyses. These methods enable the measurement and examination of various elements and aspects of scientific output, thereby allowing general evaluation and mutual comparison in the field of science and research.
Bibliometrics is most commonly applied in the assessment of scientific activity. For this purpose, various bibliometric and scientometric indicators are used (such as the Impact Factor, H-index, etc.). Among the databases that track citations on a broader scale are Web of Science, Scopus, and Google Scholar.
Below are descriptions of selected indicators you are most likely to encounter:
Article Influence Score (AIS)
AIS is similar to the Impact Factor, but it excludes self-citations and takes into account the prestige of the source journals. Citations from more prestigious journals carry greater weight. AIS is more resistant to unfair practices (e.g., "citation cartels"). There is a positive correlation between AIS and IF.
Quartile and AIS
The AIS-based quartile allows for comparison of journals within the context of this metric across a specific subject category. The AIS quartile value of a given journal can be found in the Journal Citation Reports database. The set of journals can be divided into four quartiles (Q1, Q2, Q3, and Q4). The top 25% of the most prestigious journals are found in the first quartile (Q1).
CiteScore
CiteScore measures the citation impact of sources (such as journals) in the Scopus database. The CiteScore calculation is based on the number of citations received by documents (articles, reviews, conference papers, book chapters, and data papers) published in a given journal over a four-year period, divided by the number of the same types of documents indexed in Scopus and published during those four years.
More information is available [here].
Eigenfactor Score
The Eigenfactor Score evaluates the influence of scientific publications and, based on them, the relationships between disciplines. It reflects the total number of citations to articles published in the past five years, counted in the current year. The 1,000 most prestigious journals have a score above 0.01. The sum of all Eigenfactor Scores equals 100.
The metric considers not only the number of citations but also their source—citations from more prestigious journals carry greater weight. Self-citations are not included. The Eigenfactor Score for a specific journal can be found in the Journal Citation Reports database.
More information is available [here].
H-index (Hirsch index)
The H-index is a metric that combines the number of publications with their citation impact. The value h represents the number of articles that have been cited h times or more. A complete and high-quality preparation of materials for determining the H-index requires a carefully maintained personal bibliography, including citation records.
Calculation
Publications are sorted in descending order by the number of citations. The H-index is the highest number h for which h publications have at least h citations.
Example
- Article: 10 citations
- Article: 5 citations
- Article: 3 citations
→ H-index = 3, because three articles have been cited at least three times.
Characteristics of the H-index
- Self-citations are not included.
- It varies across different databases.
- It is not suitable for interdisciplinary comparisons.
To verify your publication activity and citation impact, use citation indexes such as Web of Science or Scopus.
Impact factor (IF)
The Impact Factor (also referred to as Journal Impact Factor, JIF) is a scientometric indicator of a journal’s influence, expressing the citation rate of articles published in that journal over the previous two years. It is calculated only for journals included in the Journal Citation Reports (JCR). The calculation is based on data from the Web of Science database.
Calculation
Number of citations received in the given year ÷ Number of articles published in the previous two years
Example
For the journal Nature Reviews Microbiology (ISSN 1740-1526), the JIF value for the year 2024 is 103.3. See the journal profile in JCR.
Scimago Journal Rank (SJR)
The Scimago Journal Rank metric takes into account the prestige of the journals from which citations originate. SJR assigns a relative score to all sources within the citation network. Its methodology is inspired by the Google PageRank algorithm, in the sense that not all citations are equal. Citations from more prestigious, highly cited journals carry more weight than those from less prestigious ones. SJR is calculated using data from the Scopus database.
More information is available [here].
SNIP (Source Normalized Impact per Paper)
The SNIP metric expresses the ratio between the average number of citations and the citation potential of a field. The SNIP value of a given journal can be found in the Scopus database, either in the list of results or in the full record of an article.
More information is available [here].
Alternative Metrics (Altmetrics)
Altmetrics include a broader range of indicators than traditional metrics. They track, for example:
- Mentions on social media
- Number of downloads
- Number of views
- Saves to reference managers
Tools used for altmetrics include:
