Benjamin K. Couillard

Research

Job Market Paper

• "Build, Baby, Build: How Housing Shapes Fertility" 

  • draft available here

  • Abstract: Many developed countries face low and falling birthrates, potentially affected by rising costs of housing. Existing evidence on the fertility-housing cost relationship typically uses geographic variation (raising selection issues), neglects unit size, and says little about policy. To progress on these fronts, I first specify a dynamic model of the joint housing-fertility choice allowing choices over location and house size, estimated using US Census Bureau data. I extend `micro-moment' techniques (Petrin, 2002; BLP, 2004) both to circumvent data constraints and to incorporate heterogeneous residuals, which can prevent misspecification. Housing choice estimates confirm a Becker quantity-quality model’s predictions: large families are more cost-sensitive, and so rising housing costs disincentivize fertility. To study the causal effect of rising housing costs on fertility, I vary them directly within the model, finding that rising costs since 1990 are responsible for 11% fewer children, 51% of the total fertility rate decline between the 2000s and 2010s, and 7 percentage points fewer young families in the 2010s. Policy counterfactuals indicate that a supply shift for large units generates 2.3 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 on Marginal Revolution!

Publications 

• 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

Revise and Resubmit 

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

  • full text available here

Working Papers

• 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

• Radical Housing Reform and Dynamic Demand

  • I extend the dynamic housing demand model of Bayer, McMillan, Murphy, and Timmins (2016, ECTA) to accommodate equilibrium counterfactuals using the local housing supply elasticities estimated by Baum-Snow and Han (2024, JPE), while also leveraging the sufficient statistics results of my JMP to accommodate rich preference heterogeneity using public data. Since the residential decisions of owners depend in large part on the capital gains they expect to accrue, a supply reform that increases affordability for renters will have significant spillover effects on owners, with both effects buttressed by kinked housing supply. I have studied the model extensively and applied it to one question; now I will apply it to the question above.

  • old draft

• Abolish the Yellowbelt? Zoning Reform and Dynamic Housing Supply 

  • I study the supply impact of mass zoning reforms in Toronto allowing fourplexes and sixplexes on many properties as-of-right. I extend the dynamic housing supply model of Murphy (2018, AEJ:Policy) from single-family structures to accommodate both multiplexes and high-rises. Work on this paper so far has focused on the model, with some exploration of the data and approaches to causal identification.

  • old slides

• BLP With Heterogeneous Residuals And Zeros 

  • I build on the sufficient statistics result of my job market paper in order to make greater use of microdata in BLP-style demand estimation  and improve how zero market shares are handled. Using standard approaches, the objective function is undefined in the presence of zeros since they imply a mean utility of negative infinity. Existing microdata approaches target only parameter heterogeneity while restricting unobserved utility to be homogeneous across demographics, which can cause misspecification in some cases. The results in my job market paper imply that when microdata with individual demographics is available, even if only certain marginal distributions, then mean utilities that vary over demographic groups can be inverted out conditional on a guess for the nonlinear parameters, which delivers heterogeneous residuals and thereby avoid misspecification. Although this demographic disaggregation creates many zero group-specific market shares, moment conditions that are functions of exponentiated mean utility as in Mullahy (1997, ReStat) are still defined. 

  • Simulation results studying these alternate moment conditions are promising.