Welcome to my website! I am an applied statistician, epidemiologist, and demographer with a special interest in advanced statistical methods for counterfactual causal inference.

From July onwards I have taken on the role of Deputy Head of the Population Health laboratory of the Max Planck Institute for Demographic Research (MPIDR), where I was previously employed as a Research ScientistMJBijlsma. At the MPIDR, I am primarily concerned with applying causal inference methods to study population health and mortality, but I also study various other things, such as fertility.

MPIDR is a pure research organization, but I try to do some teaching every year, which I enjoy a lot. I have developed a Causal Mediation Analysis workshop, which I taught at the University of Helsinki in 2018 and 2019 (and will probably teach again sometime in the future). In December 2019 I developed and taught a workshop Introduction to Causal Inference to students at the European Doctoral School for Demography, in Barcelona, Spain. I will teach this again in Barcelona in December 2020 (digitally, due to COVID).

Recently, I developed an R-package named cfdecomp that performs causal mediation analysis with the g-formula: you can find the official package on CRAN, and the bones of it on my Github page. This package is based on a working paper with Nikkil Sudharsanan.

See the rest of this site for my CV, Publications, an archive of my blog posts, and my contact info.

Since I get asked questions about it: my surname comes from Frisian. A ‘Bijl’ is an axe or a hatchet, and ‘ma’ comes all the way from Old Frisian (probably) meaning ‘of the people of’. If you don’t know how to pronounce it, following English orthography just say ‘Bell-sma’ or ‘Beel-sma’ (either way is fine).