1. CWTS Leiden Ranking: An advanced bibliometric
approach to university ranking
Nees Jan van Eck
Centre for Science and Technology Studies (CWTS), Leiden University
Uppsala University
Uppsala, March 12, 2019

2. Centre for Science and Technology Studies (CWTS)
• Research center at Leiden University
• Science and technology studies, with a considerable
emphasis on scientometrics
• About 50 staff members
• Our mission: Making the science system better!
• Research groups:
– Quantitative Science Studies
– Science and Evaluation Studies
– Science, Technology, and Innovation Studies
• Commissioned research for research institutions, funders,
governments, companies, etc.
1

3. About myself
• Master in computer science
• PhD thesis on bibliometric mapping of science
• Senior researcher at CWTS
– Bibliometric network analysis and visualization
– Bibliometric data sources
– Bibliometric indicators
• Head of ICT
2

4. VOSviewer
3

5. Outline
• CWTS Leiden Ranking
• Responsible use of university rankings
4

6. CWTS Leiden Ranking
5

7. CWTS Leiden Ranking
6

8. CWTS Leiden Ranking
• Provides bibliometric indicators of:
– Scientific impact
– Scientific collaboration
• Calculated based on Clarivate Analytics Web of Science data
7

9. Selection of universities (2018 edition)
• All universities worldwide with ≥1000
Web of Science publications in period
2013–2016
• 938 universities from 55 countries
8

10. Indicators
• Size-dependent and size-independent indicators
• Scientific output:
– P
9
• Scientific impact:
– P(top 1%) and PP(top 1%)
– P(top 5%) and PP(top 5%)
– P(top 10%) and PP(top 10%)
– P(top 50%) and PP(top 50%)
– TCS and MCS
– TNCS and MNCS
• Scientific collaboration:
– P(collab) and PP(collab)
– P(int collab) and PP(int collab)
– P(industry) and PP(industry)
– P(<100 km) and PP(<100 km)
– P(>5000 km) and PP(>5000 km)

11. Differences with other university rankings
• No composite indicators
• Focused on research, not on teaching
• Based purely on bibliometric indicators; no survey data or data provided by
universities
• High-quality bibliometric methodology
• Multiple views, not just a simple list
10

12. 11

13. 12

14. 13

15. 14

16. 15

17. 16

18. 17

19. Advanced bibliometric methodology
• Field classification system
• Counting citations vs. counting highly cited publications
• Full counting vs. fractional counting
• Bibliographic database
18

20. 19
About 4000 fields of science in the Leiden Ranking
Social sciences
and humanities
Biomedical and
health sciences Life and earth
sciences
Mathematics and
computer science
Physical
sciences and
engineering

21. Why count highly cited publications?
• Leiden Ranking counts number of highly cited publications (top 10%)
• THE, QS, and US News count number of citations
• Effect of counting number of citations:
20

22. Why count highly cited publications?
21

23. Why count highly cited publications?
22
Counting citations Counting highly cited publications
Leaving out Göttingen’s
most cited publication

24. How to handle publications co-authored by multiple
institutions?
• THE, QS, and US News:
– Co-authored publications are fully assigned to each co-authoring institution (full counting)
• Leiden Ranking:
– Co-authored publications are fractionally assigned to each co-authoring institution (fractional
counting)
23
This publication is
assigned to Leiden
with a weight of 2/4

25. Why use fractional counting?
• Full counting is biased in favor of universities with a strong biomedical focus
24

26. Choice of bibliographic database:
Is more data always better?
• Universities from China, Russia, France, Germany, etc. may not benefit at all
from having more data
• Indicators should be based on a restricted database of publications
• Leiden Ranking uses Web of Science, but excludes national scientific
journals, trade journals, and popular magazines
25

27. Responsible use of
university rankings
26

28. Responsible use of university rankings
• Ten principles for responsible use
of rankings:
– Design of rankings
– Interpretation of rankings
– Use of rankings
• Covers university rankings in
general, not only the Leiden
Ranking
27
Source: www.cwts.nl/blog?article=n-r2q274

29. Responsible use of university rankings
28
Source: www.researchresearch.com/news/article/?articleId=1368350
Source: https://vimeo.com/279712695

30. Design of rankings
1. A generic concept of university performance should not be used
2. A clear distinction should be made between size-dependent and size-
independent indicators
3. Universities should be defined in a consistent way
4. University rankings should be sufficiently transparent
29

31. Design of rankings
1. A generic concept of university performance should not be used
2. A clear distinction should be made between size-dependent and size-
independent indicators
3. Universities should be defined in a consistent way
4. University rankings should be sufficiently transparent
30

32. Do not use a generic concept of university performance
31
Composite
indicator

33. Do not use a generic concept of university performance
32

34. Do not use a generic concept of university performance
33

35. Design of rankings
1. A generic concept of university performance should not be used
2. A clear distinction should be made between size-dependent and size-
independent indicators
3. Universities should be defined in a consistent way
4. University rankings should be sufficiently transparent
34

36. Distinguish between size-dependent and size-
independent indicators
What are the wealthiest countries in the world?
35
GDP per capita GDP

37. Distinguish between size-dependent and size-
independent indicators
• Shanghai, THE, QS, and US News use composite
indicators
• These composite indicators combine size-dependent
and size-independent indicators
• It is unclear which concept of scientific performance
is measured
36

38. Distinguish between size-dependent and size-
independent indicators
37

39. Design of rankings
1. A generic concept of university performance should not be used
2. A clear distinction should be made between size-dependent and size-
independent indicators
3. Universities should be defined in a consistent way
4. University rankings should be sufficiently transparent
38

40. Define universities consistently
• leiden univ
• leiden state univ
• state univ leiden
• leiden univ hosp
• state univ leiden hosp
• univ leiden hosp
• univ hosp leiden
• lumc
• univ leiden
• leiden univ med ctr
• leiden state univ hosp
• leiden observ
• sterrewacht leiden
• acad hosp leiden
• rijksuniv leiden
• rijksherbarium
• gorlaeus labs
• leiden inst brain & cognit
• leiden inst chem
• sylvius labs
• acad ziekenhuis leiden
• leiden cytol & pathol lab
• rijksherbarium hortus bot
• ...
39

41. Design of rankings
1. A generic concept of university performance should not be used
2. A clear distinction should be made between size-dependent and size-
independent indicators
3. Universities should be defined in a consistent way
4. University rankings should be sufficiently transparent
40

42. University rankings should be sufficiently transparent
41www.issi-society.org/open-citations-letter/

43. Interpretation of rankings
5. Comparisons between universities should be made keeping in mind
differences between universities
6. Uncertainty in university rankings should be acknowledged
7. An exclusive focus on ranks of universities should be avoided; values of
underlying indicators should be taken into account
43

44. Interpretation of rankings
5. Comparisons between universities should be made keeping in mind
differences between universities
6. Uncertainty in university rankings should be acknowledged
7. An exclusive focus on ranks of universities should be avoided; values of
underlying indicators should be taken into account
44

45. Interpretation of rankings
5. Comparisons between universities should be made keeping in mind
differences between universities
6. Uncertainty in university rankings should be acknowledged
7. An exclusive focus on ranks of universities should be avoided; values of
underlying indicators should be taken into account
45

46. Interpretation of rankings
5. Comparisons between universities should be made keeping in mind
differences between universities
6. Uncertainty in university rankings should be acknowledged
7. An exclusive focus on ranks of universities should be avoided; values of
underlying indicators should be taken into account
47

47. Take into account values of indicators
48
Rockefeller University
Rank 1 (PPtop 10% = 28.2%)
Queen Mary University London
Rank 50 (PPtop 10% = 14.8%)
University of Bari Aldo Moro
Rank 550 (PPtop 10% = 8.0%)
Difference in PP(top 10%) is two times larger for universities
at ranks 1 and 50 than for universities at ranks 50 and 500

48. Use of rankings
8. Dimensions of university performance not covered by university rankings
should not be overlooked
9. Performance criteria relevant at university level should not automatically be
assumed to have same relevance at department of research group level
10.University rankings should be handled cautiously, but they should not be
dismissed as being completely useless
49

49. Simplistic use of rankings
50

50. Proper use of rankings
51

51. Encouraging proper use
52

52. Conclusions
• Rankings provide valuable information...
• …but only when designed, interpreted, and used in a proper manner
• Ranking producers, universities, governments, and news media need to work
toward shared principles for responsible university ranking
53

53. CWTS Leiden Ranking 2019
• Two new types of indicators, in addition to impact and collaboration indicators
• Open access indicators (based on Unpaywall data)
– P(OA)
– P(gold)
– P(green)
– P(unknown)
• Gender indicators
– A(male)
– A(female)
– A(unknown)
54

54. Thank you for your attention!
55