Willem R. van Zwet Award for Richard Post

He received the award for the pioneering research he conducted on causal inference, which he did at the Department of Mathematics and Computer Science. On this topic, he wrote his award-winning thesis ‘Causal Effect Heterogeneity: Statistical formalization and analysis of the individual causal effect’. During his research, he was mentored by prof.dr. Edwin van den Heuvel, dean of the department. Acting as external supervisor was Hein Putter, Professor of Medical Statistics at Leiden University Medical Center.

Post chose a rather daring subject for his thesis: the subject of individual causality, or causal effect heterogeneity. The subject is controversial, since individual causal effects seem to require individual counterfactuals, which by definition are never observed. However, he described several models and assumptions in his thesis under which it is possible to see that causal effects are not the same for different individuals, and developed methods to chart the resulting heterogeneity. This causal heterogeneity is relevant in cross-sectional but also in longitudinal outcomes and survival analysis.

The jury was impressed by the broad scope encompassing both theory and applications, and was of the opinion that the exposition was very clear. The members of the jury found Post's work to be of the highest scientific quality, in the sense that it had mathematical rigor as well as intuitive explanations. The thesis distinguished itself by strong modelling and being conceptually highly innovative. It was cited as a particular strength that relevant applications all illustrated this. In conclusion the jury wanted to mention that the thesis was also very well written.