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.

Selected Work in Progress

Regional Identity in Organisations: Vertical Alignment on the Western Front of WW1

with Oliver Brufal (University of Groningen)

Soldiers in conscripted armies have low incentives to exert effort; the reward for doing so is small, and the potential cost (death) is incalculable. We investigate whether shared regional identity between soldiers and officers can alter the incentive problem. We test this hypothesis using data on all French WW1 fatalities. We use a data-driven approach to infer cultural regions from surnames; soldiers and officers are considered aligned if they were born in the same region. We estimate the effect of losing alignment in a design-based difference-in-difference setup. Conditional on the regiment and battle, whether a dead officer was regionally connected is quasi-random. Within-regiment variation shows mortality declines among treated soldiers. The effect is concentrated among officers with distinctly regional names, that are non-migrants, supporting a behavioural mechanism. Our results suggest that shared identity with superiors incentivises agents to exert greater effort.

Draft expected 2026Q1.

Presentations: Cambridge EH Graduate Seminar, LSE SPEECH, University of Groningen. University of Mannheim.
Selection and Evolutionary Growth in pre-Industrial Germany

Evolutionary growth theory (i.e., Galor and Moav 2002, Clark 2007) posits that natural selection set the stage for modern growth. I leverage micro-data from historical Germany to assess the viability of the selection mechanisms. I estimate fertility differentials and the inter-generational transmission of SES. High status couples, proxied by occupation, had 1-2 additional children, and SES was strongly heritable. To explore whether these parameters induce selection, I simulate an overlapping generation model of fertility choice and status transmission. The German parameters do not enable Clark's survival of the richest, whereas Galor and Moav's selection on quality can arise if the returns to investing in child quality are sufficiently large. Monte Carlo simulations extend the analysis beyond Germany. Survival of the richest requires exceptionally high coefficients of transmission (0.87), and selection on quality emerges whenever returns to quality investments translate into higher fertility.

Draft expected 2025Q4.

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

Presentations: South Denmark University.

Research Experience

December 2024 - December 2025
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

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

Presentations

Past:

2025
University of Mannheim. CEPR Public Health Interventions in the Long Run. South Denmark University. LSE SPEECH. CEPR Applied Micro-Economic History Workshop. LSE Demography.
2024
Cambridge Graduate Seminar. IEA Conference. IPECE Workshop.