Sebastian Ernst

Sebastian Ernst

I am a PhD candidate at the London School of Economics. My research interests are in public economics, industrial organization and labor economics.

I will be on the academic job market in 2026-27.

Working Papers

Subsidy Design in Equilibrium: Theory and Evidence from Child Care

Job Market Paper Draft coming soon

Risk or Responsiveness? Targeting in Unemployment Policy with Andreas I. Mueller, Johannes Spinnewijn and Joost Bollens

This paper evaluates the use of algorithmic risk profiling to direct job search support toward individuals most at risk of long-term unemployment. Using three regression discontinuity designs and rich administrative data from the Flemish Public Employment Service (VDAB) in Belgium, we address two key dimensions: whom and when to target. First, job search counseling raises employment on average, but treatment effects decline sharply with predicted risk. This reveals a fundamental trade-off between targeting those most at risk and those most responsive to intervention. Second, we find no evidence that treatment effects depreciate at the individual level, but strong dynamic selection: as spells lengthen, surviving job seekers have both higher baseline risk and lower treatment responsiveness, with opposing implications for the returns to treatment. We develop and calibrate a conceptual framework for optimal targeting that highlights the key role of the ratio of predicted treatment effects to predicted job-finding probabilities. Targeting rules combining both objects substantially outperform the status quo, yielding welfare gains nearly three times as large as those from random assignment, while targeting on risk scores alone performs worse than random assignment.

Work in Progress

Hiring Subsidies for Older Job Seekers: Evidence from Belgium with Joost Bollens

Publications

Risk Scores for Long-Term Unemployment and the Assignment to Job Search Counseling with Andreas I. Mueller and Johannes Spinnewijn, AEA Papers and Proceedings, 114: 572–76, May 2024

Replication Package
This paper analyses how risk profiling is used to assign unemployed job seekers to job search counseling in Flanders, Belgium. We compare algorithmic selection to self-selection and selection by job search counselors. We discuss practical challenges for the implementation of risk profiling and highlight avenues for further research. We find that algorithmic assignment is used for only a small fraction of the sample and that job search counselors appear to have valuable private information on job seekers' reemployment prospects beyond what is captured by the algorithmic risk score.