Methods for Calculations in Reports

Source Data

The source data have the following characteristics:

  • The analysis includes the following types of documents recorded in Web of Science (WoS): Article, Review, Letter. Additional information also considers the number of contributions in conference proceedings (Proceedings papers).
  • The analyzed documents come from journals listed in these Web of Science (WoS) indexes, which are part of the Journal Citation Reports (JCR):
    • Science Citation Index Expanded (SCIE)
    • Social Sciences Citation Index (SSCI)
    • Arts & Humanities Citation Index (AHCI)
  • The primary dataset is sourced from the WoS database. The national register of outputs (IS VaVaI) adds extra details, mainly about research organizations (especially faculties) and the main research fields of authors.

Article Influence Score

The key metric in this analysis is the Article Influence Score (AIS), which reflects how influential a journal is based on citations. It comes from the Web of Science database and is part of the Journal Citation Reports (JCR). Its logic roughly corresponds to the established 5-Year Journal Impact Factor metric but differs in that citations are weighted: citations of articles in prestigious journals carry greater weight in AIS calculation, and vice versa. Furthermore, AIS does not count citations within the same journal. For these reasons, AIS is a robust metric compared to other indicators, as it is relatively resistant to unethical citation practices.

AIS Assignment

Each article takes on the AIS score of the journal it was published in that year.1. You can find current and past AIS scores in the Journal Citation Reports (JCR) and the provided materials.

Field Assignment

JCR records a field classification for each journal, which is adopted by the analyzed articles. WoS and JCR primarily use the WoS Categories classification, which includes more than 254 fields. National evaluation primarily uses the OECD classification (Fields of Research and Development - FORD), which contains significantly fewer fields (39). A conversion table used in the Web of Science database ecosystem (JCR and InCites) facilitates the translation between WoS Categories and OECD-FORD.

A journal has only one AIS value. Therefore, the number of assigned fields to a journal or the classification system used does not affect this value—it remains the same. However, its quartile ranking may vary depending on the classification system or the journal’s fields.

Determination of Quartile Ranking

We rank journals based on AIS and group them into quartiles. Here’s how it works:

  1. Journals without an AIS are excluded, and duplicate occurrences of the same journal within a single FORD field are also removed.2.
  2. Journals within a given FORD field are ranked based on their AIS values, and the resulting sequence is divided into top decile and quartiles.3.
  3. Each article is paired with its respective journal for the given year of publication, thus inheriting its quartile position in the relevant field.

Research Field Personnel Capacities

The calculations are based on two key data points recorded in the national database IS VaVaI:

  • Unique author identifier. The national author identifier (VEDIDK) is available only for Czech and Slovak citizens. For foreign researchers, we use ORCID (or, where applicable, Research ID or Scopus ID).
  • Research field of the outputs. Authors specify a research field for each output they submit to IS VaVaI. For each researcher, we compile a list of all their outputs over a five-year period from the national database—not just the ones included in the bibliometric analysis. The predominant research field of these outputs determines which field they are assigned to.4.

For national field-level analyses, all outputs of a researcher are considered, regardless of institutional affiliation. However, when analyzing specific research institutions, only outputs officially recorded for that institution are included. If a researcher is affiliated with multiple institutions, their recorded output may vary by institution, which can also affect their field classification.

Determining Productivity

The productivity data have the following characteristics:

  • Productivity is measured in the top journal tiers (top decile, Q1, Q2) of each field.
  • The outputs can help identify key research institutions in different fields. However, the data have limited significance for institutions with very few research outputs and/or small staff numbers.
  • The data are not suitable for tracking the productivity of individual researchers. That’s why we only present aggregated results, not individual-level data.
  • The journal ranking (but not the field classification) of articles is taken from the I. Report. If an article is classified in multiple fields and has different rankings, we use the highest ranking in this analysis.
  • The fields for productivity (see II. Report) are based on the authors’ research classification—not the classification of journals or articles in WoS (or JCR). So, the charts reflect the productivity of mathematicians, chemists, economists, etc., at a given institution, even if their articles were published in journals classified under different fields (e.g., a mathematician publishing in an economics or information science journal). Productivity is calculated based on the total number of individuals working in a given field at an institution and the number of articles they have published in the top journal tiers. In the charts, productivity is expressed as a percentage, showing the deviation from the national average productivity in that field, which is represented by a baseline value of 100%.
1. So-called Early Access articles are not included in the analysis; they are only considered after being published in a regular journal issue.
2. For example, the prestigious journal Cell is classified under WoS Category Cell Biology as well as Biochemistry and Molecular Biology. Both disciplines fall under FORD 1.6 Biological Sciences, so it is recorded only once in that category.
3. This process also determines the AIS threshold values that separate the observed tiers, which are published in Appendix 1 of the field reports. Threshold values are established separately for each field and each year. Over time, AIS thresholds remain relatively stable, allowing the prediction of a journal’s likely future quartile ranking based on its AIS. Even if a journal’s AIS changes significantly, affecting its position, quartile boundaries within fields tend to be relatively stable.
4. If a researcher has an equal number of outputs in multiple fields, we remove the oldest records and repeat the process until only one field remains. If necessary, this is done iteratively as long as at least one record is available. In rare cases where this method doesn’t resolve the issue, the researcher is assigned to both fields.