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About us Faculty of Science and Engineering PhD ceremonies

Modelling population behaviour

PhD ceremony:K. Frieswijk
When:June 21, 2024
Supervisors:M. (Ming) Cao, Prof, prof. dr. ir. J.M.A. (Jacquelien) Scherpen
Where:Academy building RUG
Faculty:Science and Engineering
Modelling population behaviour

Those who choose climate conscious behaviour, weigh their individual investment against the common interest. But their behaviour in turn affects others who might choose to act in favour of a common goal. In her PhD thesis, Kathinka Frieswijk asks herself the question: How does responsible behaviour arise and propagate in scenarios where individual interests conflict with global ones?

Frieswijk developed novel mathematical models that integrate human behavioural dynamics. Through these models, she studied the evolution of large-scale populations in the context of i) the spread of recurrent epidemic diseases such as covid-19, ii) sexually transmitted infections (STIs), and iii) climate change. 

Frieswijk explored factors that positively impact population behaviour, including health-protective behaviour during epidemics, condom use for STI prevention, and environmentally responsible behaviour in the context of climate change. She studied the effect of testing campaigns, vaccination campaigns, and physical distancing behaviour on infection prevalence and local outbreak control. 

Frieswijk analytically derived conditions under which local outbreaks will be extinguished. If these conditions are not satisfied, the disease becomes endemic, and Frieswijk can compute the infection prevalence at the endemic equilibrium. Her results emphasise the importance of testing campaigns and responsible population behaviour for local outbreak control. Vaccination campaigns are crucial in alleviating hospital strain by decreasing the prevalence of individuals with severe symptoms. Additionally, Frieswijk demonstrated that risk perception significantly influences epidemic spread. Under certain conditions and high levels of risk perception, there are periodic epidemic outbreaks.