I am a PhD Student in the Economic History department at the LSE. My research interests lie in Economic History, Population Economics, and Political Economy.

I am a member of the Historical Economic Demography group, and am supervised by Eric Schneider and Tom Raster.

I will be visiting UCLA Economics from Spring 2026.

You can find my CV here. Email: j.p.ohler@lse.ac.uk

Working Papers

Build Better Health: Evidence from Ireland on Housing Quality and Mortality

with Alan de Bromhead (UCD) , and Ronan Lyons (TCD)

Poor housing conditions, and the negative effects of Household Air Pollution (HAP) in particular, remain one of the most pressing global public health challenges. While the association between poor housing and health has a long history, evidence of a direct link is lacking. In this paper, we examine a rare example of a public housing intervention in rural areas, namely the large-scale provision of high-quality housing in Ireland in the late 19th and early 20th centuries. We exploit a novel dataset of deaths-by-disease and deaths-by-age-and-sex over the period 1871–1919, to test the impact of the intervention on mortality. Our difference-in difference estimates indicate that improved housing conditions reduced mortality by as much as 1 death per 1000. This effect is driven by reductions in deaths from respiratory diseases. We propose a likely mechanism that is consistent with the pattern of results we observe: a reduction in Household Air Pollution through improved housing quality and better ventilation. A cost-benefit analysis reveals that the scheme was a highly cost-effective intervention.

[ CEPR DP ] [ LSE WP ]

Presentations: LSE Demography Seminar, CEPR Applied Micro-Economic History Workshop, CEPR Public Health Interventions Workshop.

Work in Progress

Regional Identity and Motivation: Evidence from the Trenches of WWI

with Oliver Brufal (University of Groningen)

Mission-oriented organizations rely on social incentives in the absence of high-powered pecuniary incentives. We identify a novel social incentive with significant impact on motivation. We present evidence on how agents' motivation is affected when they share personal traits - in our setting localized regional identity - with a principal. Using individual‐level data on all French WWI fatalities, we estimate the effect of losing such connection. In a design-based difference-in-difference setup we exploit within-regiment variation across regional groups. We find that soldiers (agents) are more motivated when a principal (officer) with a shared identity is present. Placebo treatments - a random draw of non-connected officers dying - support a causal interpretation of our results. Heterogeneity analysis reveals that regional network effects matter most for minority groups in non-diverse regiments. By exploring how our effect varies across regions we can also speak to the determinants of regional cultural identity in France in the early 19th century.

Draft expected 2025Q4.

Presentations: Cambridge EH Graduate Seminar, LSE SPEECH, University of Groningen*.
Fertility, Mobility, and Growth: The demographic underpinnings of evolutionary endogenous growth in pre-industrial Germany

Reproductive inequality - the fertility differential between poor and rich couples - together with intergenerational mobility shapes class structure. Still, few studies evaluate these dynamics in a joint framework. Evolutionary growth theories such as Galor & Moav (2002) or Clark (2007) argue that fertility differentials contributed to the spread of certain growth-enhancing traits, eventually resulting in modern economic growth. However, they do not explicitly account for regression to the mean in economic status. By leveraging the demographic records of 150,000 individuals from pre-industrial Germany, I estimate reproductive inequality and social mobility. High status couples had more surviving children, with their status closely related to their parents' position in the socio-economic distribution. By combining my estimates of reproductive inequality and social mobility I simulate an overlapping generation model to explore the parameter space that enables the demographic mechanisms that underpin evolutionary growth theories.

Draft expected 2025Q4.

Subsumes: Malthus in Germany? Reproductive Success and Status in pre-industrial Germany

Presentations: South Denmark University.

Research Experience

December 2024 - ongoing
Research Assistant to Eric Schneider.
Build OCR pipeline for the automated transcription of handwritten historical tables.
October 2023 - June 2024
Research Assistant to Ronan Lyons.
Worked on Urban Economics and Irish Economic History. Used advanced NLP and OCR methods for data transcription.
August 2021 - August 2022
Research Assistant to Tomas Cvrcek.
Transcribed historical sources from the Austro-Hungarian empire and worked with ArcGIS to geocode data.

Teaching Experience

September 2025 - ongoing
Intermediate Quantitative Methods (Postgraduate)
London School of Economics - Department of Methodology

Presentations

Upcoming:

2nd December
University of Mannheim
TBA

Past:

2025
CEPR Public Health Interventions in the Long Run. SDU Economics. LSE SPEECH. CEPR Applied Micro-Economic History Workshop. LSE Demography.
2024
Cambridge Graduate Seminar. IEA Conference. IPECE Workshop.