April 30, 2026 | News | Blog@MPIDR

My Internship at the MPIDR

Johann Behrendt was a visiting researcher at the Max Planck Institute for Demographic Research (MPIDR) in Rostock from February to April. He is currently studying psychology in Leipzig. In the MPIDR blog, he describes his experiences as a research intern gaining an insight into a scientific discipline other than his own.

Waterfront picture of the Institute building

When I arrived in Rostock for my six-week internship in mid-February, it was pouring rain. So, I spent my first afternoon in the guest apartment, frantically trying to crash-course the most basic vocabulary of demography: birth rate, TFR, quantum, and so on. Because the truth is: I have no idea about demography.

In almost three years of studying psychology, I’ve dealt with the activation of brain areas and the occurrence of various perceptual phenomena or memorized the symptoms and etiology models of different mental disorders. But the terms fertility, mortality, and migration? I only know them from the news. So why did I come to the MPI in Rostock? I asked myself that very question for a brief moment on that rainy afternoon. But ever since my school days, I've had a strong interest in looking at broader societal contexts—a perspective that naturally often falls short in the individually focused field of psychology. And since I feel that psychology can provide important explanations for demographic trends, the MPIDR felt like a place where my various interests could intersect.

A person stands in front of a modern glass building with clean lines and reflective windows on a sunny day.

Johann Behrendt talks about his experiences as an intern at the MPIDR.

Nevertheless, I felt like an imposter during those first few days. I was eating lunch with people doing impressive research in demography, while I had to have the concept of a hazard curve explained to me. After the first Lab Talk, my head was spinning, and I spent the next hour looking up all sorts of vocabulary (salmon bias, etc.).

In the second week, the sun came out (and not just metaphorically): Kelsey, as my tutor, creates a really friendly atmosphere, and Angela helps me with my statistics, and Henrik cleares up any remaining questions. I made progress with R, reviewed literature, and familiarized myself with Kelsey and Angela's paper, which I was there to help with. In the third week, I applied the Two-Time-Scales Model developed by Angela to Italian data, estimating the risk of a first child depending on the age at the start of the relationship and the duration of the relationship.

Whenever I wasn't working on the paper with Kelsey and Angela, there were always exciting thematic inputs on the agenda through the Lab Talks or workshops. Still, there was enough time in the afternoons to let the PhD students and postdocs show me my limits at table tennis.

Another highlight were the many opportunities to talk with the scientists and staff: Henrik told me about his career path, Karolina gave me an insight into data management and data privacy, Steffen talked to me about psychological variables in demographic research, Heiner explained the PhD programs at the MPIDR, Jonas impressed me with a (brief) glimpse into his Markov extension of the Lee-Carter model, and in conversations with Josephine and Marcus, I learned more about the intersections between demography and health.

In the end, the six weeks flew by, and the conclusion is an easy one: it was a very exciting, inspiring time in which I learned a lot (a more routine use of R, a functioning workflow for literature reviews, but also an improved forehand in table tennis ;)) and gained real insight into how things work at the MPIDR. (A more extensive conclusion is in the appendix)

When I left Rostock in early April, it was raining again (or still?).