CWTS is an interdisciplinary institute at Leiden University. Its research staff come from a broad and diverse spectrum of specialized academic fields ranging from psychology, political science, literature studies and information science to computer science, economics, physics and chemistry.

Academic Staff

Clara Calero-Medina

Researcher and coordinator of contract research projects. Clara's research work is related with network analysis applied to scientific publications, particularly citations and co-authorship networks for the study of research performance.

Rodrigo Costas

Researcher. Rodrigo's research focuses mostly on the development and application of new bibliometric tools and the new field of 'altmetrics'.

Nees Jan van Eck

Researcher and Head of ICT. Nees Jan's research focuses on the development of visualization tools and algorithms, mainly for analyzing the structure and development of science.

Thomas Franssen

Postdoctoral researcher. Thomas is interested in evaluation and quantification practices. Inspired by cultural sociology as well as science and technology studies, Thomas analyzes the ways in which researchers are evaluated and evaluate themselves, and the (numerical) devices that are used to do so.

Evan de Gelder

Research assistant to Inge van der Weijden in the working group CPPS. Evan's research focuses on career paths of young scientists and their job perspectives outside academia, in order to make recommendations for young scientists, universities and companies.

Julia Heuritsch

Researcher. Julia’s research focusses on the analysis of the subsequent careers of PhD holders.

Tjitske Holtrop

Postdoctoral researcher. Tjitske studies the practices of evaluation: how are questionnaires made, what do numbers do, how are reports written or what happens in meetings?

Wout Lamers

Research assistant. Wout’s main interests lie in dynamics of knowledge production.

Thed van Leeuwen

Senior researcher and coordinator of the Social Sciences, Humanities & Law (WISSH) working group. Thed's research focuses on the development of indicators for the research assessment of scholarly activity in the social sciences, the humanities, and law. He is co-editor the OUP journal Research Evaluation.

Ingeborg Meijer

Researcher and coordinator of the Society Using Research (SURe) working group. Ingeborg focuses on the development of proxies, tools, and indicators to assess the uses of research in society; in public, professional, and private domains.

Barend van der Meulen

Endowed professor Evidence for Science Policy, CWTS, and Head of Research at the Rathenau Instituut. Barend’s research focuses on instruments of science policy making and the changes in the profession of science.

Ed Noyons

Researcher and operational director CWTS B.V. Ed's main research interests involve structures and mappings of science and their use in science policy and research management, field delineation, and  multi-dimensional impact analysis, in particular societal impact of science.

Andrea Reyes Elizondo

Research assistant. Andrea’s research focusses on different academic and health science systems and the relationships between them.

Sarah de Rijcke

Associate professor and deputy director of CWTS, and coordinator of the Evaluation Practices in Context (EPIC) working group. Her research focuses on the growing use of assessment procedures and bibliometric indicators in scientific and scholarly research, and the effects on knowledge production.

Alex Rushforth

Postdoctoral researcher. Alex's research concerns how governance changes impact modern science. At present this has taken him to explore the effects that formal evaluations and new metric indicators are having on research in academic institutions.

Clifford Tatum

Researcher and member of the Science and Evaluation Studies (SES) working group. Clifford’s research is focused on Open Science in relation to emerging evaluation practices and research information systems.

Robert Tijssen

Professor of Science & Innovation Studies. Robert's research interests focus on the multidimensional dynamics of knowledge flows, linkages, and interactions between the public sector and the private sector, between science and innovation.

Vincent Traag

Researcher. Vincent's research focuses on complex networks and social dynamics. He holds a Master in sociology and a PhD in applied mathematics, and tries to combine the two in his work.

Martijn Visser

Researcher and PhD candidate. Martijn's research focuses on data sources for the measurement of research performance.

Ludo Waltman

Researcher and deputy director of CWTS, and coordinator of the Advanced Bibliometric Methods (ABM) working group. Ludo's research interests focus on bibliometric methods, in particular the analysis and visualization of bibliometric networks and the development of bibliometric indicators.

Inge van der Weijden

Researcher and coordinator of the Career Policy & Paths in Science (CPPS) working group. Inge conducts research on the motivation, selection, and evaluation of scholars in order to better understand career development of scientists. She is responsible for the CWTS press communication.

Bert van der Wurff

Jos Winnink

PhD candidate. Jos's research focuses on early stage identification of scientific breakthroughs to better understand the interface between science and technology.

Paul Wouters

Director of CWTS and professor of Scientometrics. Paul is interested in how evaluation systems have developed and are creating new constraints for the development of knowledge. He is also interested in the history of science in general and the role of information systems in these histories in particular.

Alfredo Yegros

Researcher and member of the CWTS project board. Alfredo's research interests include the analysis of public-private research interactions and knowledge flows, the study of science-technology linkages, and the study of methods that potentially able to capture societal impact of scientific research.

Zohreh Zahedi

PhD candidate. Zohreh is doing research on altmetrics (alternative metrics and tools) and investigating potential of using altmetrics for measuring research performance.

Jochem Zuijderwijk

PhD candidate. Jochem is working on a PhD thesis that focuses on the formative effects of new incentive and reward systems in biomedicine within the Science and Evaluation Studies (SES) group.



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Visiting Academic Staff

Cornelis van Bochove

Emeritus professor of Science Policy Studies. Cornelis focuses on the impact of various types of research and development activities on economic growth and on the career system in research.

Kevin Boyack

Visiting researcher and president of SciTech Strategies, Inc. His research focuses on the detailed mapping of literature and other data sources, and on establishing the accuracy of those maps.

Giovanni Colavizza

Visiting PhD student from the Digital Humanities Laboratory of EPFL. Giovanni’s research focuses on the bibliometric analysis of the historiography on Venice in the last century and a half, with special attention on the use of both primary and secondary sources over time.  

Björn Hammarfelt

Visiting postdoctoral researcher. Björn’s current research focuses on evaluation systems and university rankings as examples of an emerging “metric culture” in academia. He is also interested in the use, and misuse, of bibliometric measures on the humanities.

Stefan de Jong

Reasearch fellow. Stefan’s research interests are the relationship between science policy and academic research, focusing on societal impact and evaluation of academic research.

Vincent Larivière

Associate professor at Université de Montréal and visiting professor at CWTS. At Université de Montréal, Vincent holds the Canada Research Chair on the Transformations of Scholarly Communication.

Marc Luwel

Visiting researcher. Marc's research focuses on performance-based funding in higher education and measuring outcome and impact of publicly funded research.

Tina Nane

Visiting researcher. Tina's research focuses on the statistical analysis and modeling of bibliometric data and citation networks.

Ton Nederhof

Visiting researcher. Ton's research focuses on research evaluation and bibliometric analysis in general (including in the social sciences and humanities).

Ton van Raan

Emeritus professor of Quantitative Studies of Science. Ton's research focuses on the application of bibliometric indicators in research evaluation, science as a self-organizing complex system, statistics of bibliometric indicators, ranking and benchmarking of universities, and mapping of science.

Cassidy Sugimoto

Associate professor at Indiana University Bloomington and visiting professor at CWTS. Cassidy’s research focuses on scholarly communication and scientometrics.

Cathelijn Waaijer

Visiting researcher. Cathelijn’s research focuses on science education and study performance in medical school.



Technical Staff

Henri de Winter

Web developer. Henri has over 10 years of experience developing web applications with the Microsoft .NET framework. His current work focuses on frontend developing with JavaScript (e.g. Ext JS, JQuery) and backend developing with the ASP.NET MVC framework.



Marketing & Sales Staff

Mark Neijssel

Sales director CWTS B.V. Mark is responsible for the development of the contract research activities for research performance studies, network analyses, and science mapping studies, as well as tailor-made training courses for clients.



Administrative Staff

Suze van der Luijt-Jansen


Anne Marie van Noord


Petra van der Weel

Management assistant


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