In this PhD-thesis several new and existing data science application are described that are particularly focused on applications for tax administrations.

This dissertation explores how Large Language Models (LLMs) can effectively and responsibly contribute to complex decision-making processes. By combining AI and human intelligence, Hybrid Intelligence (HI) emerges, allowing the strengths of both humans and machines to be utilized.

We explored the Universe using weak gravitational lensing, a phenomenon that occurs when light from distant galaxies is bent by the gravitational fields of closer cosmic objects, much like how a lens distorts light.

Humans can see the world through the eyes of other humans and imagine what they know, want, and intend. This competence is known as Theory of Mind.

Classical statistical methods, such as p-values, are difficult for researchers to apply correctly. They for example do not allow drawing conclusions from a study early, or for extending a study with extra research groups that want to make their data available later.

Carbonaceous asteroids preserve a record of early solar system processes, where minerals and organic molecules, like polycyclic aromatic hydrocarbons (PAHs), offer clues to planetary evolution and prebiotic chemistry.

Continuous optimization is never easy: the exact solution is always a luxury demand and the theory of it is not always analytical and elegant.

Assistant Professor Juan Masullo of the Institute of Political Science has been awarded the 2025 Alexander George Best Article Award for his work on interviews and process tracing.

Childhood trauma can have a lifelong effect. Many therapists do not dare to confront these vulnerable patients with their past because they are concerned that the patients will be unable to cope. Research has now shown that exposure therapy can be helpful for this group of people.

Astronomers in Leiden have used the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile to produce a new detailed image of the centre of our Milky Way. This allows them to investigate the life of stars in the most extreme region of our galaxy. The Leiden scientists, led by Katarzyna…

Netherlands and China can learn from each other to handle household and livestock wastewater more sensibly. In the FOREWARD project, scientists from Leiden, Wageningen, and China are working together with local partners on feasible solutions that advance the environment, health, and economy.

Human language is constantly evolving with its linguistic structure being shaped by language users at both individual and population levels. Focusing on the interplay between processes of language acquisition and communicative need in shaping human languages, this thesis introduces a novel computational…

Promotor: Prof.dr. E. F. van Dishoeck, Co-promotor: A. N. Heays

Evidence-informed policy-making is crucial for good governance. Yet, despite the abundance of evidence from research and evaluation available to decision-makers, we know little about the actual influence of evidence on government policies. The ‘Power of Evidence’ (PoE) research programme, directed by…

Flying is cheaper than driving a car, but a disaster for the environment. Yet few politicians dare to levy excise duty on kerosene. This is only one example from a world where emotions and yelling are burying facts, and in which scientists lose connection with society.

What started as an idea during a social gathering led to an unexpected breakthrough in research on resistant bacteria. Biologists and chemists from Leiden developed a new substance that proves to be effective against bacteria resistant to antibiotics. They published their discovery in Nature Chemist…

If European countries rely solely on technological advances, they won't be able to limit global heating to 1.5 degrees. Households will also need to change their lifestyles. This 'inconvenient truth' is the result of calculations done by industrial ecologist Stephanie Cap. ‘It's not a popular message,…

Not all sustainable business models have the impact they claim, Leiden researcher Levon Amatuni revealed. Car sharing and phone reuse, for example, have a smaller positive effect than previously thought. Amatuni advises people to ‘pay attention to actual changes in their consumption behaviour rather…

Hydrogen can help to solve the climate problem. At least, if we start producing it in the right, clean way. Leiden researchers mapped out the global environmental impact of hydrogen production and looked ahead to 2050. They published their work in Energy & Environmental Science.

Do you often feel drained after a day at the office? The new SPS Monitor measures how sensitive you are to various stimuli. Psychologist Véronique de Gucht developed the questionnaire. 'I want to demystify high sensitivity.'

What if AI doesn’t just support engineers, but actually works alongside them? A large consortium, including Leiden University, gets 3.7 million euros. They will explore novel synergies between engineers and AI, in industrial engineering design areas such as automotive engineering.

This thesis focuses on addressing four research problems in designing embedded streaming systems.

High sensitivity, or sensory processing sensitivity, is increasingly discussed in popular media, but what does it actually mean to be highly sensitive? In this episode, Véronique de Gucht, associate professor at Leiden University, shares her expertise on this topic.

Have you ever seen your friend smiling, and suddenly you started grinning too? PhD student Chris Riddell is researching how and why we copy body language. As a new Face of Science, he will take us along on his research journey for the coming year.

Recently, Prime Minister Dirk Schoof caused quite the stir in the political arena of The Hague following the release of policy documents on the asylum debate. This came ahead of a decision that had not yet been made. The question has since arisen as to whether it’s still possible for civil servants…

Overlevingsanalyse is een onderzoeksgebied dat zich richt op het bestuderen van de tijd tot het optreden van een specifieke uitkomst.

Promotor: Prof.dr. W.Th.F. den Hollander, Co-promotor: R. Fernandez

Professor of Social and Organisational Psychology Carsten de Dreu has been awarded an Advanced Grant by the European Research Council. This subsidy of 2.5 million euros will allow De Dreu to carry out research on the causes of conflicts between groups at both macro- and micro-level.

The Executive Board of the Institute of Psychology has a new Director of Operational Management. It’s the perfect role for Paula van den Bergh. ‘For me, “connection” is a nice word. If you see the connections between things, you immediately see the logic behind the processes.’ Her career has taken her…

Lecture, Ancient History Research Seminar

Lotte Melenhorst, PhD candidate at Leiden University’s Institute of Political Science, has been granted a Top Student Award by the International Communication Association's (ICA) Political Communication Panel for her paper on the role of the media in the legislative process. This was announced in May…

By making smart use of available data, the health and care of people can be substantially improved. Marco Spruit wants to use language and machine learning in the coming years to identify and solve the biggest care issues in the region of The Hague. He has been appointed Professor of Advanced Data Science…

LIACS receives grant from Intel for research and development of innovative technology to program multi-processors.

The widespread idea that politics is mediatised needs to be revised. Although media attention heavily influences some political processes, this is not the case when it comes to lawmaking. Lotte Melenhorst, a political scientist at Leiden University, analysed three heavily covered legislative processes…

PhD defence

Arco Timmermans is Professor by special appointment Public Affairs at the Institute of Public Administration. On Dutch television programme 'EenVandaag', he discussed the remarkable changes that have been made in a report on lung cancer in and around the Dutch city of Beverwijk that was presented by…

A million people in the Netherlands attempt to quit smoking each year, often without lasting success. Health psychologist Kristell Penfornis carried out doctoral research into the role of self-image in smoking cessation. “If smoking is normal in your social circle, it more easily becomes part of your…

PhD defence

Lecture