Research

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Working Papers

ABSTRACT: In response to surging immigration pressure in Europe and the United States, Western policymakers advocate foreign aid as a means to fight the 'root causes' of irregular migration. This article provides the first global evidence of the effects of aid on migration preferences, migration flows, and possible underlying mechanisms, both in the short and longer term. We combine newly geocoded data on World Bank aid project allocation at the subnational level over the period 2008-2019 with exceptionally rich survey data from a sample of almost one million individuals across the entire developing world and data on migration and asylum seeker flows to high-income countries. Employing two distinct causal estimation strategies, we show that in the short term (after the announcement of a World Bank project and within two years after project disbursement), foreign aid improves individual expectations about the future and trust in national institutions in aid-receiving regions, which translate into reduced individual migration preferences and asylum-seeker flows. In the longer term (between three to five years after disbursement), foreign aid fosters improvements in individual welfare through poverty reduction and income increases, resulting in larger regular migration to high-income countries. Our findings show that aid can cause a short-lived reduction in migration aspirations, except in fragile Sub-Saharan African contexts where aid appears largely ineffective. In contrast, foreign aid enhances individual capabilities over the longer term, contributing to greater regular migration, consistent with the 'mobility transition' theory.

Media coverage: Devex, IfW, Kieler Nachrichten (German), WDR (German), Welt (German)


ABSTRACT: This paper studies how social networks (might fail to) shape agricultural practices. We exploit (i) a unique census of agricultural production nested within delineated land parcels and (ii) comprehensive social network data within four repopulated villages of rural Vietnam. In a first step, we extract exogenous variation in network formation from home locations within the few streets that compose each village (populated through staggered population resettlement), and we estimate the return to social links in the adoption of highly-productive crops. We find a large network multiplier, in apparent contradiction with low adoption rates. In a second step, we study the structure of network formation to explain this puzzle: social networks display large homophily, and valuable links between heterogeneous households are rare. Due to the clustered nature of networks and the dynamic, endogenous propagation of agricultural practices, there are decreasing returns to social links, and policies targeting "inbetweeners" are most able to mitigate this issue.


ABSTRACT: Agricultural productivity is low in rural economies compared to that of developed economies, and there is disparity in measured productivity across farms. The dispersion of measured productivity might reflect (i) volatile conditions and (ii) sluggish adjustments in agricultural production to such conditions, e.g., due to market frictions or technological constraints. This paper sheds light on the existence and nature of such imperfect adjustments by measuring the adjustment of production (factors, inputs and cropping patterns) to large shocks affecting the returns to different crops, and by estimating a dynamic structural model of farm production. We use the model to quantify the extent to which market frictions and technological constraints respectively limit the ability of farmers to adjust their production to changing conditions. We find that both technological and market frictions are quantitatively relevant, the latter implying that a significant part of sluggish adjustments can be interpreted as misallocation in factors and in cropping patterns.

Publications

6. Forecasting Bilateral Asylum Seeker Flows with High-dimensional Data and Machine Learning Techniques (with Konstantin Boss, Tobias Heidland, Finja Krüger, and Conghan Zheng), BSE Working Paper No. 1387, 2023. Conditionally accepted Journal of Economic Geography.

We develop monthly asylum seeker flow forecasting models for 157 origin countries to the EU27, using machine learning and high-dimensional data, including digital trace data from Google Trends. Comparing different models and forecasting horizons and validating out-of-sample, we find that an ensemble forecast combining Random Forest and Extreme Gradient Boosting algorithms outperforms the random walk over horizons between 3 and 12 months. For large corridors, this holds in a parsimonious model exclusively based on Google Trends variables, which has the advantage of near real-time availability. We provide practical recommendations how our approach can enable ahead-of-period asylum seeker flow forecasting applications. 


JEL classification: C53, C55, F22 

Keywords: forecasting, refugee flows, asylum seekers, European Union, machine, learning, Google trends 

5. Immigration, Labor Markets and Discrimination: Evidence from the Venezuelan Exodus in Perú (with Gianmarco Leon and Steven Stillman), BSE Working Paper No. 1350; World Bank Policy Research Working Paper No. 9982. World Development, vol. 174, 106437, 2024.


Venezuela is currently experiencing the biggest crisis in its recent history. This has led more than 7.3 million Venezuelans to emigrate, at least 1.5 million of those to Peru, which amounted to an increase of over 4 percent in the Peruvian population. Venezuelan immigrants in Peru are relatively similar in cultural terms, but, on average, more skilled than Peruvians. In this paper, we first examine Venezuelans' perceptions of being discriminated against in Peru. Using an instrumental variable strategy, we document a causal relationship between the level of employment in the informal sector - where most immigrants are employed - and reports of discrimination. We then study the impact of Venezuelan migration on local's labor market outcomes, reported crime rates, and attitudes using a variety of data sources. We find that inflows of Venezuelans to particular locations led to increased employment and income among locals, decreased reported crime, and improved reported community quality. We conduct a heterogeneity analysis to identify the mechanisms behind these labor market effects and discuss the implications for Peruvian immigration policy.


JEL classification: F22, J15, O15, R23

Keywords: Immigration, forced migration, discrimination, labor markets, Peru, Venezuela

Media coverage: World Bank, BSE Focus

4. Monitoring War Destruction from Space Using Machine Learning (with Jonathan Hersh, Andrea Matranga, Hannes Mueller and Joan Serrat). Proceedings of the National Academy of Sciences of the United States of America (PNAS), June 8, 2021, vol. 118(23). [UNGATED] [data] 

Existing data on building destruction in conflict zones rely on eyewitness reports or manual detection, which makes it generally scarce, incomplete, and potentially biased. This lack of reliable data imposes severe limitations for media reporting, humanitarian relief efforts, human-rights monitoring, reconstruction initiatives, and academic studies of violent conflict. This article introduces an automated method of measuring destruction in high-resolution satellite images using deep-learning techniques combined with label augmentation and spatial and temporal smoothing, which exploit the underlying spatial and temporal structure of destruction. As a proof of concept, we apply this method to the Syrian civil war and reconstruct the evolution of damage in major cities across the country. Our approach allows generating destruction data with unprecedented scope, resolution, and frequency—and makes use of the ever-higher frequency at which satellite imagery becomes available.

Keywords: Conflict, Destruction, Deep Learning, Remote Sensing, Syria

Media coverage: Nature, El Pais, The Times, Digital affairs, El Español, UAB, Techmonitor, CSIC, Eldiario, COPE, MSN, AQUI, Siglo de Torreon,  Catalunya Vanguardista, Siglo XXI, Republica, Diario Libre, EFE

3. Easy Come, Easy Go? Economic Shocks, Labor Migration and the Family Left Behind, Journal of International Economics, vol. 128, 103409 , 2021. [UNGATED] [data] [appendix]

This article investigates the impact of negative income shocks in migrant destination countries around the world on the domestic and international labor migration decisions of their family members left behind at origin. Exploiting differences in labor market shocks across and within destinations during the Great Recession, I find large and heterogeneous effects on both types of migration decisions. Poor migrant households reduced domestic and increased international labor migration in response to the shock. Rich migrant households remained largely unaffected. I provide a theoretical framework, which rationalizes this heterogeneity by the relative magnitudes of income and substitution effects caused by the shock. The results imply a deterioration in the skill selection of aggregate international migrant flows as poor households had below average skill levels. New international migrants targeted the same destinations as established ones from the same household, providing evidence of strong kinship migration networks. Changes in migration also led to an increase in intimate partner cohabitation and fertility among poor families. The results show that domestic and foreign migration decisions are interrelated and jointly determine household outcomes. 

JEL-classification: F22, J13, J61, O15, R23

Keywords: International Migration, Domestic Migration, Labor Supply, Migrant Selection, Fertility, Unemployment, Vietnam

Media coverage: Barcelona GSE Focus

2. Searching for a Better Life: Predicting International Migration with Online Search Keywords (with Marcus Böhme and Tobias Heidland), Journal of Development Economics, vol. 142, 102347, 2020. [UNGATED] [appendix] [data]

Migration data remains scarce, particularly in the context of developing countries. We demonstrate how geo-referenced online search data can be used to measure migration intentions in origin countries and predict migration flows. Our approach provides strong additional predictive power for international migration flows when compared to reference models from the migration and trade literature. We provide evidence, based on survey data, that our measures partly reflect genuine migration intentions and that they outperform any of the established predictors of migration flows in terms of predictive power, especially in the bilateral within-dimension. Our findings contribute to the literature by (1) providing a novel way for the measurement of migration intentions, (2) allowing real-time predictions of current migration flows ahead of official statistics, and (3) improving the performance of conventional models of migration flows.

JEL-classification: F22, C82, J61, O15

Keywords: International Migration, Migration Intention, Google Trends

Media coverage: Medium, Barcelona GSE, Social observatory of "la Caixa", GIS Lounge

We analyze how internal labor migration facilitates shock coping in rural economies. Employing high-precision satellite data, we identify objective variations in the inundations generated by a catastrophic typhoon in Vietnam and match them with household panel data before and after the shock. We find that, following a massive drop in income, households cope mainly through labor migration to urban areas. Households with settled migrants ex ante receive more remittances. Nonmigrant households react by sending new members away who then remit similar amounts than established migrants. This mechanism is most effective with long-distance migration, while local networks fail to provide insurance.

JEL-classification: J61, O15; P25, P36, Q54, R23

Keywords: Risk Sharing, Internal Migration, Natural Disasters, Vietnam

Other Publications


Assessing LISFLOOD-FP with the next-generation digital elevation model FABDEM using household survey and remote sensing data in the Central Highlands of Vietnam (with Hawker, L., Neal, J., Savage, J., Kirkpatrick, T., Lord, R., Zylberberg, Y., Thuy, T. D., Fox, S., Agyemang, F., and Nam, K. P.), Nat. Hazards Earth Syst. Sci., 24, 539–566,  2024.

The Vietnamese-Chinese Migration Industry in Angola: A Case Study (with Rainer Klump), in: Asian-African Encounters, Amsterdam University Press, 2017.

Selected Work in Progress

Advances in Monitoring War Destruction (with Clément Gorin and Hannes Mueller)

School, Work or Marriage? Agricultural Shocks and Gender Gaps in Child Development  (with Hanna Wang)