I'm an associate professor and teach at the Psychological and Mathematical Institutes of Leiden University. My research is about statistics, machine learning and psychological assessment. 

I work on decision-tree methods, because the results are relatively easy to understand, even by non-statisticians.  While black-box methods from machine learning and AI have improved our ability to predict using (big) data, a current big challenge is how to obtain human-understandable scientific knowledge from  them. My group develops methods to do so.

I develop open-source software packages for the programming environment R (links on left or GitHub). My work has been published in journals like Psychological Methods, the Journal of Statistical Software, Information Fusion and World Psychiatry (see links on the left or Google Scholar), and has been covered in popular media outlets (see links on the left). As Mary-Jo and the Support Vector Machines, I make music videos about statistical methods (see links on the left or YouTube).