Leiden Ranking

Key Facts

Published by Selection Criteria

Centre for Science and Technology Studies, Universität Leiden

Top 500 universities based on Leiden indicators
Data Basis & Methodology Indicators
Thomson Reuters database, Web of Science (WoS)
- Only natural and social sciences. Arts and humanities are excluded for methodological reasons
- Only the following publication types are considered: articles, letters and reviews

Bibliometric analysis

Information on methodology
  • Mean citation score (MCS). The average number of citations of publications written by members of a university.
  • Mean normalized citation score (MNCS). Average number of citations of publications written by members of a university, adjusted to reflect differences in discipline, publication year and document type.
  • Proportion top 10% publications (PPtop 10%). Proportion of publications written by members of a university that are among the 10% most frequently cited publications and that are similar to other publications. Publications are deemed similar if they come from the same area of research, were published in the same year, and if they are the same type of document.
International research collaboration
  • Proportion collaborative publications (PPcollab). Percentage of co-authored publications by academics from one or more foreign institutions.
  • Proportion international collaborative publications (PPint collab). Percentage of co-authored publications by academics from two or more countries.
  • Mean geographical collaboration distance (MGCD). Average geographical distance to the international co-authors.
  • Proportion of long distance collaborative publications (PP>1000 km). Proportion of publications with a geographic distance of over 1000 km between co-authors.


The methodology and data used in the Leiden Ranking are very transparent, and the inconclusive nature of the final results is clearly indicated (see data basis). And, because the methodology changes from year to year, the editors discourage a longterm comparison of results.

A unique factor of the Leiden Ranking is the current possibility of excluding non-English language articles when interpreting the data. This is because such publications necessarily have a smaller readership and are consequently less likely to be cited, leading to statistically irrelevant results.

A problematic point concerns treating geographical aspects when assessing joint research projects. Here it must be noted that Australian universities occupy the top ranks en bloc. The question arises as to whether the high ranking is a sign of excellence in research and research collaboration, or rather the fact that Australian universities are traditionally linked to other Commonwealth countries, and that the geographical distances between Australia and most other countries in the Commonwealth are quite large.