The economy, the climate and social networks are all examples of complex systems made up of many components that interact with one another and are connected in networks. Complexity theory examines the collective behaviour that characterises such a system, which may be the spread of infections or the dissemination of opinions. Pijpers: ‘This can lead to a better understanding of important phenomena in society and the economy. This theory is interesting for CBS as it allows complex phenomena to be more effectively described from a statistical perspective. This is why the topic of complexity has been part of the CBS research programme since 2016.’ Pijpers is the manager of this research programme.
‘Complexity science has its roots in the 1980s and 1990s,’ according to Pijpers. ‘So it is still a young field of study. In this discipline we seek to gain a deeper understanding of complex phenomena, discover the links between trends and use these to find solutions for a variety of social issues. One example is the study that CBS conducted together with the municipality of The Hague into the social networks of young people in The Hague and the relationship between crime and the social structures of those young people. Another CBS study looks at informal care provided by those in a person's own social network. This study identified where older people live, which older people have children and how far away these children live. This can yield important information about the healthcare that older people require.’
Bridge between CBS and science
In his new position as professor in complexity by special appointment, Pijpers hopes to build a bridge between CBS and science in the field of complexity. ‘In this position, I work one day a week at UvA, where I divide my time between the Korteweg-de Vries Institute for Mathematics (KdVI) and the Institute for Advanced Study (IAS), where I conduct research, teach and supervise PhD candidates and students. These institutes carry out internationally renowned research in the area of complexity, algebra, geometry and mathematical physics. This is a perfect combination for mobilising knowledge.’ According to Pijpers, CBS is a world leader in the area of complexity research. ‘Other statistical agencies – such as the Australian – are very interested in this subject and now also want to put it on the international agenda.’
The IAS of the University of Amsterdam was founded in 2016 with the aim of carrying out research into complex issues that transcend the boundaries between faculties. One of the important instigators was the then-mayor of Amsterdam, Eberhard van der Laan. The renowned Institute offers scientists a safe haven where they can focus on important fundamental and social issues free of the traditional boundaries between disciplines. Peter Sloot, Professor of Complex Adaptive Systems at UvA and scientific director of the IAS: ‘Research is often instigated by a single discipline while the most urgent scientific issues require knowledge from multiple fields. Think of issues such as climate change, immigration and economic crises, for example. All of these are issues that you need to approach with scientists from a variety of disciplines.’ According to Sloot, it is important that they learn to speak the same language to be able to create something new together. ‘The common denominator in the IAS is complexity science.’
We live in a complex world where everything is interconnected and where it is difficult to distinguish between cause and effect. Sloot: ‘Complexity science allows us to discover causal links in those cross-linked relationships and perform numerical predictions on the outcomes of possible interventions.’ Understanding which intervention is needed to bring about a specific outcome is one of the most urgent and challenging issues of our time, says Sloot. ‘Interventions require three things: a deep understanding of the problem, an abundance of data and, lastly, mathematical models for computer simulations. In practice this means performing an analysis, such as an analysis of a problem in the city, and then using predictive numerical models to determine which policy will have the desired effect and consequently resolve the issue.’
CooperationIn a wide variety of areas – from school segregation to criminal networks and from diabetes to mental healthcare – the IAS is working with municipalities, ministries and other organisations. Strong ties have also been maintained with CBS for some time now. Sloot: ‘The former Director General of CBS was a member of our external advisory group, which also included scientist Robbert Dijkgraaf. Our cooperation with CBS goes beyond merely collecting and analysing data. Modelling complex cause-effect relationships and networks is the heart of our research. We share much substantial common ground. In an effort to make the cooperation more concrete, in January 2021 CBS and the IAS entered into a strategic partnership with a specific research agenda and Frank Pijpers was named professor of complexity for official statistics by special appointment. Furthermore, the new Director General of CBS, Angelique Berg, was recently appointed a member of our Board of Trustees.’ Finally, Pijpers emphasises that the role of CBS in this partnership is to stress test models: ‘The best method to test models is to decide on which model outputs can be measured in the real world, and collect and use the data for that in the most optimal way’.
CV Frank Pijpers
Frank Pijpers studied astronomy at Leiden University and obtained his PhD in complex mass loss processes of old stars. He then worked in Denmark and the United Kingdom on the mathematics of inversion problems in academia. After this, he transferred to the British ministry of education, where he worked with statistical models. On joining CBS, he started as a project leader in the social security team. He is currently part of the methodology team at CBS, where he works on complexity theory and other subjects.