By Yeo Pin Pin, Head, Research Services
We first covered the Leiden Rankings last year, but back then SMU was not included at the time This has now changed.
SMU is now one of the universities included in the Leiden Ranking Open Edition, which was released in October 2025. Due to a more inclusive approach that now includes core and non-core publications (see definition) in the OpenAlex database, the Leiden Ranking Open Edition 2025 now includes 2,831 universities (from 120 countries). To be included in these rankings, a university needs to have at least 1,500 "core or non-core publications" indexed in OpenAlex from 2020-2023.
Traditional vs Open Editions of the CWTS Leiden Ranking
There are in fact two different editions of the Leiden Ranking, besides the Open Edition which uses the OpenAlex Data, there is also the Leiden Ranking Traditional Edition 2025, which uses the more traditional Web of Science indexed publications.
The traditional edition only includes 1,594 universities (from 77 countries) and Universities are included only if they have produced at least 800 Web of Science indexed "core publications" in the period 2020–2023.
As explained in our piece last year, Core publications are defined as a subset of journals indexed in the Web of Science Core collection also defined as of "international scope" with "a sufficiently large number of references to other core journals". SMU did not meet the criteria of the traditional edition and was not listed.
Why does the Open Edition version exist? The main driver for the shift to using OpenAlex is CWTS's strategic goal to be based on open research information and provide research analytics that offer a more inclusive perspective on the global academic landscape (Leidenmadtrics 2025). This was a shift away from using proprietary data to using open data and open source algorithms (Open Data New Wire, 2024).
Also a unique selling point of Leiden Ranking (both editions) is the sole use of data on research publications and the use of various bibliometric indicators without any data submitted by the universities or survey data like in QS Ranking.
A look at SMU in Leiden Ranking Open Edition
Using the Scientific impact indicators, SMU had 20% of publications with at least 10 citations and 0.8% of publications with over 100 citations
Not surprising that about 25% of SMU publications are in non-core sources, with 99% in English and about 70% of publications are in journals.
The Open access (OA) indicators showed that SMU had 52% green OA publications, 10% gold OA and 8% hybrid OA.
For the same period 2020-2023, the collaboration indicators showed that 81% of publications have interorganisational collaboration, 73% have international collaboration, and 4% have industry collaboration.
You can explore the Leiden Ranking Open Edition at https://open.leidenranking.com/ and the Traditional Edition at https://traditional.leidenranking.com/
References
The CWTS Leiden Ranking 2025 - More open, more inclusive, more informative (2025, October). Leidenmadtrics. Available at: https://www.leidenmadtrics.nl/articles/the-cwts-leiden-ranking-2025-more-open-more-inclusive-more-informative
Introducing the Leiden Ranking Open Edition. (2024, January 30). Open Data News Wire. https://opendatanewswire.com/research-impact/2024/01/30/introducing-the-leiden-ranking-open-edition/
