Math major Abby Ostriker modeled city growth for the Netherlands Bureau for Economic Policy Analysis
Abby discovered the best way to navigate Holland: by bike.

About the host

Centraal Planbureau (CPB) is an government agency that is unique in the Netherlands for being officially independent of the central government. It provides a second opinion on the economic consequences of proposed laws, and also performs research on future public policy issues. In addition, they provide economic forecasts for the country and Europe as a whole. There are 5 sectors at CPB:  Public Finance, Macroeconomics, Labor and Education, Competition and Regulation, and Climate and Regional Economics.

My project

Policy-makers are interested in city growth, but currently very little is known about what the important forces are. To learn more about whether there are one or two key economic factors influencing growth or whether it is all just driven by randomness, I studied two purely stochastic models of city growth.

I spent the first part of my internship reviewing the literature on existing stochastic models. As I was reading the papers, I also wrote summaries of the models, both of the math and the economic assumptions underlying the models. This both helped my understanding of the material and built a foundation for future people who might work on this project as well. This part involved a lot of math and felt like a CI-M (but in a good way! I like writing.)

In the second part of my project, I wrote a computer simulation to  check that we could replicate the results of the mathematical models. I also tested whether either of the models were useful for predicting city sizes in the future. This part involved a lot of programming, and I learned a new language, R. 

Result and lasting impact

The final product of my internship is a 30-page paper that will be used internally to direct discussions in the organization about the future of the project. I also presented my work to the sector in order to introduce the idea to the rest of the team. Currently, there is a large conversation in Dutch politics about the role of the government in encouraging city growth, which the CPB needs to decide whether to pursue. My presentation and paper will spark a conversation in the department about what other avenues of research they could pursue. Eventually, the goal is to help them decide how strong the natural forces of city growth are and whether it would be wise for the government to try to counteract them.

Value of the language

I also made an effort to learn Dutch because I wanted to be able to understand the conversations of my colleagues at lunch or the coffee machine. For the first month or so I didn’t have much success, but when I started reading Harry Potter in Dutch with an English copy for reference, I made a surprising amount of progress. I can now understand a lot of simple Dutch sentences, such as the conversation of some Dutch family friends, and I am quite proud of my progress.

  • Netherlands
  • Internship
  • Math