Current Research

Current Research


Refugees and development: Evidence from Tanzania
(with Jean-François Maystadt)
Journal of Economic Geography, forthcoming.   Abstract  
We exploit a 1991–2010 Tanzanian household panel to assess the effects of the temporary refugee inflows originating from Burundi (1993) and Rwanda (1994). We find that the refugee presence has had a persistent and positive impact on the welfare of the local population. We investigate the possible channels of transmission, underscoring the importance of a decrease in transport costs as a key driver of this persistent change in welfare. We interpret these findings as the ability of a temporary shock to induce a persistent shift in the equilibrium through subsequent investments rather than a switch to a new equilibrium in a multiple-equilibrium setting.

The costs of agglomeration: House and land prices in French cities
(with Pierre-Philippe Combes and Laurent Gobillon), Review of Economics Studies, forthcoming.   Abstract  
We develop a new methodology to estimate the elasticity of urban costs with respect to city population using French house and land price data. After handling a number of estimation concerns, we find that the elasticity of urban cost increases with city population with an estimate of about 0.03 for an urban area with 100,000 inhabitants to 0.08 for an urban area of the size of Paris. Our approach also yields a number of intermediate outputs of independent interest such as the share of housing in expenditure, the elasticity of unit house and land prices with respect to city population, and distance gradients for house and land prices.

Urban form and driving: Evidence from US cities
(with Matthew Turner)
Journal of Urban Economics, forthcoming.   Abstract  
We estimate the effect of urban form on driving. We match the best available travel survey for the us to spatially disaggregated national maps that describe population density and demographics, sec- toral employment and land cover, among other things. To address infer- ence problems related to sorting and endogenous density, we develop an estimator that relies on assumption of imperfect mobility and exploit quasi-random variation in subterranean geology. The data suggest that increases in density cause small decreases in individual driving. Apply- ing our estimates to the observed distribution of density and driving in the us suggests that plausible densification policies cause decreases in aggregate driving that are small, both absolutely and relative to what might be expected from gas taxes or congestion charging.

The production function for housing
(with Laurent Gobillon and Pierre-Philippe Combes)   Abstract  
We propose a new non-parametric approach to estimate the production function for housing. Our estimation treats output as a latent variable and relies on the first-order condition for profit maximisation with respect to non-land inputs by competitive house builders. For parcels of a given size, we compute housing by summing across the marginal products of non-land inputs. Differences in non-land inputs are caused by differences in land prices that reflect differences in the demand for housing across locations. We implement our methodology on newly-built single-family homes in France. We find that the production function for housing is reasonably well, though not perfectly, approximated by a Cobb-Douglas function and close to constant returns. After correcting for differences in user costs between land and non-land inputs and taking care of some estimation concerns, we estimate an elasticity of housing production with respect to non-land inputs of about 0.80.

Place-based policies for development
(with Anthony J. Venables)   Abstract  
Many development policies, such as placement of infrastructure or local economic development schemes, are “place-based.” Such policies are generally intended to stimulate private sector investment and economic growth in the treated place, and as such they are difficult to appraise and evaluate. This paper sets out a framework for analyzing the effects of such policies and assessing their social value. It then reviews the literature on place-based policies in the contexts of transport improvements, economic corridors, special economic zones, lagging regions, and urban policies.

Mobility and congestion in urban India
(with Prottoy A. Akbar, Victor Couture and Adam Storeygard)   Abstract  
We develop a methodology to estimate robust city-level vehicular mobility indices, and apply it to 154 Indian cities using 22 million counterfactual trips measured by a web mapping service. There is wide variation in mobility across cities. An exact decomposition shows this variation is driven more by differences in un-congested mobility than congestion. Under plausible assumptions, a one-standard-deviation improvement in uncongested speed creates much more mobility than optimal congestion pricing. Denser and more populated cities are slower, only in part because of congestion. Urban economic development is correlated with better (uncongested and overall) mobility despite worse congestion.

Delineating urban areas using building density
(with Marie-Pierre de Bellefon, Pierre-Philippe Combes and Laurent Gobillon)   Abstract  
We develop a new dartboard methodology to delineate urban areas using detailed information about building location, which we implement using a map of buildings in France. For each pixel, our approach compares actual building density after smoothing to counterfactual smoothed building density computed after randomly redistributing buildings. We define as urban any area with statistically significant excess building density. We also define the urban cores of these urban areas in a similar manner. Finally, we develop novel one- and two-sided tests to provide a statistical basis to compare maps with different delineations, which we use to document the robustness of our approach and large differences between our preferred delineation and the corresponding official one.

The misallocation of land and other factors of production in India
(with Ejaz Ghani, Arti Grover Goswami, and William Kerr)   Abstract  
This paper quantifies the misallocation of manufacturing output and factors of production between establishments across Indian districts during 1989–2010. It first distills a number of stylized facts about misallocation in India, and demonstrates the validity of misallocation metrics by connecting them to regulatory changes in India that affected real property. With this background, the study next quantifies the implications and determinants of factor and output misallocation. Although more-produc- tive establishments in India tend to produce more output, factors of production are grossly misallocated. A better allocation of output and factors of production is associ- ated with greater output per worker. Misallocation of land plays a particularly important role in these challenges.
Urban growth and its aggregate implications (with Diego Puga)   Abstract  
We develop an urban growth model where human capital concentration promotes entrepreneurship and raises city productivity. Land-use regulation balances commuting and housing costs against productivity gains to benefit local residents. Systematic determinants and productivity shocks drive city growth, generating realistic city-size distributions. Cities experience parallel growth in expectation, while subject to ups and downs around this common trend. Growth of exist- ing cities and net city entry accommodate aggregate population growth. Matching key empirical moments at the city and economy-wide levels, we explore the contribution of cities to aggregate growth and income levels and the economy-wide consequences of land use regulations.
Measuring the cost of congestion in a highly congested city: Bogotá (with Prottoy Akbar)
Abstract and paper forthcoming.
The roadway of US metropolitan areas (with Erick Guerra)
The lifecycle of land: Evidence from the US, 2000-2010 (with Henry Overman, Diego Puga, Tanner Regan, and Matthew Turner)
Growth in cities revisited
The economic effects of high-speed trains (with Laurent Gobillon and Miren Lafourcade)