Benjamin K. Couillard

Research

Job Market Paper

• Couillard, Benjamin K. (2026). "Build, Baby, Build: How Housing Shapes Fertility" 

  • draft available here

  • Abstract: Fertility in the developed world has fallen far below replacement, and rising housing costs are a natural suspect as a driver of child quality expenditure. Most studies use geographic comparisons that conflate the fertility impact of a local housing cost shock with sorting of families who would have had children either way. In this paper, I use Beckerian microfoundations to specify a demand model for housing and children that leverages fertility-induced shifts in housing demand to identify the impact of rents on fertility net of geographic sorting. Larger families demand more housing, making their location decisions more sensitive to rents as household budgets are more stressed, so that growth in rents hurts the value of having a large family the most. Estimation exploits the statistical sufficiency of limited observed data from the U.S. Census Bureau for rich heterogeneity in housing demand at the neighborhood level. I find that the elasticity of aggregate births with respect to average rents is -0.3. Had real rents not risen over 1990-2020, 9 million (7%) more children would have been born, 76% of the 2020 gap with replacement fertility would be erased, and 5.5pp more young adults would have started families in 2020. Policy counterfactuals indicate that a supply shift for large units generates 3.4 times more births than an equal-cost shift for small units. This analysis concludes that the supply of housing suitable for families can meaningfully contribute to demographic sustainability.

  • Media coverage:

    • News media: The New York Times, The Economist, Toronto Star, Vox, La Presse, City Journal, Irish Independent, Europe 1, Newsweek, New York Post, Blick, NewsNation, Investopedia, Realtor.com, Townhall, ZME Science, Conflits, El Liberal, The MortgagePoint, Forum Nadlan USA.

    • Policy organizations: American Enterprise Institute, Institute for Family Studies, California YIMBY, Missing Middle Initiative, Mackinac Center for Public Policy, Pacific Research Institute, Independent Institute, Fondation IFRAP, Iona Institute, Boyd Institute, Zentrum für neue Sozialpolitik, Observatoire de l’immigration et de la démographie, European Large Families Confederation.

    • Blogs and newsletters: Marginal Revolution, Don’t Worry About the Vase, The Abundance and Growth Blog, Brandon Donnelly, Illuminating Fertility, Pencilling Out, Peter Copeland, Free Markets and Firepower, vv.guide.

  • Old version (subject of most media coverage) available here

Publications 

• Brodeur, Abel; Derek Mikola; Nikolai Cook; Replication Games collaborators, incl. Benjamin K. Couillard (2025). “Mass Reproducibility and Replicability: A New Hope.” Nature. IZA Discussion Paper No. 16912.

  • full text available here

• Couillard, Benjamin K.; Christopher L. Foote; Kavish Gandhi; Ellen Meara; Jonathan Skinner (2021). “Rising Geographic Disparities in US Mortality.” Journal of Economic Perspectives, 35(4): 123–146. 

  • full text available here

Working Papers

• Couillard, Benjamin K. (2026). "Decomposing Racial Disparities in Pollution Exposure." 

  • draft available here

  • Abstract: Racial minorities in the United States bear disproportionate exposure to environmental hazards, but the extent to which this reflects race itself versus correlated economic and demographic characteristics remains unknown. I decompose racial disparities in pollution exposure using a Bayer et al. (2007) neighbourhood sorting model estimated on a four-decade national panel of harmonized census tracts, with preferences varying over race, income, tenure, age, and presence of children. To estimate this heterogeneity from public data, I exploit the sufficiency of observed marginal distributions for the first-stage log-likelihood. Counterfactuals that reweight each minority group’s non-racial demographics to match the white distribution reveal that these characteristics explain little of the disparity: no demographic variable meaningfully accounts for racial gaps in PM10 exposure, and tenure—a proxy for wealth—accounts for only 15–30% of disparities in proximity to Toxic Release Inventory facilities, with other variables adding negligible additional explanatory power. These results weigh against the view that racial pollution disparities primarily reflect rational sorting given fewer economic resources, and point instead toward race-specific mechanisms including discriminatory siting, constrained choice sets, or heterogeneous preferences for unobserved amenities correlated with pollution.

• Couillard, Benjamin K. (2026). "Identification From Marginal Distributions In Logit Models With Observed Heterogeneity."

  • draft available here

  • Abstract: In this paper I study identification of logit discrete choice models from marginal distributions alone. In fields like urban economics that use these models, unobservability of the joint distribution of agent choices and characteristics is treated as a binding data constraint, whereas in empirical industrial organization marginal distributions are used to circumvent that constraint and as the form in which microdata enters estimation. I borrow from the contingency table literature to provide necessary and sufficient conditions for point-identification of logit models with observed heterogeneity from marginal distributions. These results also show that in models without random coefficients, the standard assumption in empirical IO of residual homogeneity almost surely results in an empty identified set. I verify these predictions using Monte Carlo simulations. 

• Couillard, Benjamin K. & Christopher L. Foote (2019). “Recent Employment Growth in Cities, Suburbs, and Rural Communities.” Federal Reserve Bank of Boston Working Paper No. 19–20.

  • full text available here

Works in Progress

• Couillard, Benjamin K. (2026). "Rehabilitation Codes, Rental Supply, and the Demand for Neighborhoods." 

  • draft available on request