Welcome! For anyone who is interested in my work as a scientist, I developed this site.
My main area of interest in the field of statistics is the modelling of interaction effects in prediction problems. While many statistical models focus on the unique effects of predictive factors on one or more outcome variables, my challenge is to explore the way in which the combined influences of factors on an outcome can be assessed. A few of my special interests are:

  • Treatment-subgroup interactions: interaction effects between a treatment variable and person characteristics indicating that a treatment effect differs for different groups of persons
  • Tree-based models, recursive partitioning
  • Meta-analysis and moderator effects
  • Prediction
  • Predictive validity and reliability
  • Regression and classification
  • Patient-tailored therapy
  • Artificial Intelligence

Besides my statistics research, I like working together with behavioural and medical scientists. Transforming research problems into data analysis strategies and extracting the essential information from large data sets is a challenge I enjoy. More recently, I have become involved in discussing research outcomes with other experts from different fields and, where possible, transforming scientific knowledge into tools for use in everyday practice.

Since August 2015, I am an associate professor in the Methodology and Statistics group at the Institute of Psychology, Leiden University, the Netherlands. This is a great job!