T. Ryan Johnson

About Me

I combine large administrative datasets, GIS, and formal models of choice to study how institutions shape behavior. To measure their effects, I use game theory and spatial models to disentangle institutional influence from individual and collective choice.

My work on US politics focuses on elections, like how voter and candidate behavior changes after primary reform in California, Washington, and St. Louis, as well as how turnout responds to natural hazards like flood risk. My methodological work relates to borders and territory, drawing on case studies from Peru, South Africa, Sierra Leone, and Kenya, as well as cross-national studies of democracy and civil war. My published work compares agriculture across 151 countries and models espionage between states.

I received my Ph.D. in Political Science from Washington University in St. Louis in May 2026. In 2025 I was a Mathematical Statistician at the U.S. Census Bureau. I have been an Adjunct Instructor in the Department of Computer Science at Saint Louis University since 2024.

My research has appeared in Economica and the Journal of Theoretical Politics. Part of my dissertation was supported by the Weidenbaum Center on the Economy, Government, and Public Policy.

Research Interests

• Political Economy: borders and territory, representation and electoral systems
• Methodology: Bayesian machine learning, causal inference, formal theory, spatial statistics

Publications

• bin Oslan, Afiq and T. Ryan Johnson (2026). “Spies in a barrel: When to reel in espionage.” Journal of Theoretical Politics 38 (2), 87–109. https://doi.org/10.1177/09516298251403415
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• Johnson, T. Ryan and Dietrich Vollrath (2020). “The Role of Land in Temperate and Tropical Agriculture.” Economica 87 (348), 901–937. https://doi.org/10.1111/ecca.12335
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Working Papers

• Gaussian Processes for Spatial Confounding
• Kriging for Robust Standard Errors
• Limited Ballot Participation After a Top-Two Primary
• Sophisticated Voting in an Approval Primary
• Spurious Spatial Econometrics

Work in Progress

• Estimating the Random Coefficients Logit with Voter Files
• Flood Risk and Turnout (with Guillermo Rosas and Dihan Shi)

Teaching

Saint Louis University, Department of Computer Science

• Databases (CSCI 4710/5710), Fall 2026
• Introduction to Computer Science: Taming Big Data (CSCI 1070), Fall 2024

Saint Louis University, Department of Earth and Atmospheric Sciences

• Introduction to Geographic Information Systems (GIS 4010/5010), Fall 2024

Washington University in St. Louis, Department of Political Science

• TA for PhD courses:
  • Math Camp, Summer 2021 and 2022
  • Applied Statistical Programming (Pol Sci 5625), Spring 2022
  • Formal Models of Political Institution (Pol Sci 5082), Fall 2021
  • American Political Institutions (Pol Sci 520), Fall 2021
  • Causal Inference (Pol Sci 5024), Spring 2021
  • Computational Social Science (Pol Sci 583), Fall 2020
  • Theories of Individual and Collective Choice II (Pol Sci 506), Spring 2020
  • Mathematical Modeling (Pol Sci 5052), Fall 2019

Sam Houston State University, Department of Mathematics & Statistics

• Developmental Mathematics II (MATH 0332), Fall 2011–Spring 2013

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