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G’day. I am an experimental economist studying paternalism, the economics of freedom, and public support for policy. I combine formal economic models with incentivized experiments, using belief and preference elicitation to distinguish between competing explanations of behavior. I care about methods a whole lot, which is why I share my code and materials, use pre-analysis plans and preregistrations, and have worked on replications.
I am currently a Research Fellow in the Department of Economics at the University of Melbourne, where I also manage the Experimental Economics Laboratory (E²MU). Previously, I managed the Cologne Laboratory for Economic Research for over five years.
I also develop open-source tools for experimental research: uproot for running behavioral experiments and ego for bringing machine behavior into experiments with human participants. Before these, I worked on z-Tree unleashed.
At the University of Melbourne, I teach Experimental Economics with classroom experiments I build in uproot. Alongside the course, I write Econ Really Matters, short handouts that each take one piece of economic theory and work out what it implies for personal decisions, public policy, or research design.
Before I joined the University of Melbourne, I was an Oskar Morgenstern Fellow at the Mercatus Center at George Mason University and held visiting positions at the Vinson Centre, University of Buckingham, and at Pontificia Universidad Javeriana in Bogotá, Colombia. I obtained my doctorate in economics from the University of Cologne, where I was supervised by Axel Ockenfels. I also completed a master’s degree in economics and a bachelor’s degree in business administration at the University of Cologne, and studied abroad at the University of Texas at Dallas.
Publications in peer-reviewed journals
Experimental Economics (2026) · Journal version · GitHub · Interactive experiment builder · Abstract [−] Abstract [+] · Citation [−] Citation [+]
Large Language Models (LLMs) have the potential to profoundly transform and enrich experimental economic research. We propose a new software framework, “alter_ego”, which makes it easy to design experiments between LLMs and to integrate LLMs into oTree-based experiments with human subjects. Our toolkit is freely available at github.com/mrpg/ego. To illustrate, we run differently framed prisoner's dilemmas with interacting machines as well as with human-machine interaction. Framing effects in machine-only treatments are strong and similar to those expected from previous human-only experiments, yet less pronounced and qualitatively different if machines interact with human participants.
@article{ego,
title = {{Integrating machine behavior into human subject experiments: a user-friendly toolkit and an application to framed prisoner's dilemmas}},
author = {Engel, Christoph and Grossmann, Max~R.~P. and Ockenfels, Axel},
journal = {Experimental Economics},
year = {2026},
pages = {1--16},
doi = {10.1017/eec.2025.10038},
keywords = {mrpg},
} Management Science (2023), 70(3):1343-1356 · Journal version · Citation [−] Citation [+]
@article{fivsar2024reproducibility,
title = {{Reproducibility in {\it Management Science}}},
author = {Fi{\v{s}}ar, Milo{\v{s}} and Greiner, Ben and Huber, Christoph and Katok, Elena and Ozkes, Ali I and {Management Science Reproducibility Collaboration}},
journal = {Management Science},
year = {2024},
volume = {70},
number = {3},
pages = {1343--1356},
publisher = {Informs},
doi = {10.1287/mnsc.2023.03556},
keywords = {mrpg},
} Journal of Behavioral and Experimental Finance (2020) · Journal version · Abstract [−] Abstract [+] · Citation [−] Citation [+]
We present z-Tree unleashed, a novel approach and set of scripts to aid the implementation of computerized behavioral experiments outside the laboratory. z-Tree unleashed enables subjects to join the experiment using a web portal that requires no software apart from a web browser. Experimenters are likewise enabled to administer their experiments from anywhere in the world. Except for z-Tree itself, z-Tree unleashed is entirely based on free and open-source software. In this paper we give a high-level overview of z-Tree unleashed’s features and benefits and its design. We also show how to set up the server and demonstrate the steps required for conducting an entire experiment. We subsequently explain how to leverage the security and routing features of a virtual private network with z-Tree unleashed, enabling servers to securely run behind routers.
@article{zTu,
title = {{{\it z-Tree unleashed}: A novel client-integrating architecture for conducting z-Tree experiments over the Internet}},
author = {Duch, Matthias L. and Grossmann, Max~R.~P. and Lauer, Thomas},
journal = {Journal of Behavioral and Experimental Finance},
year = {2020},
volume = {28},
pages = {100400},
publisher = {Elsevier},
doi = {10.1016/j.jbef.2020.100400},
url = {https://www.sciencedirect.com/science/article/pii/S2214635020303270},
issn = {2214-6350},
keywords = {mrpg},
}