Academic Research

O'Clery, N., Gomez-Lievano, A. & Lora, E., 2016. The Path to Labor Formality: Urban Agglomeration and the Emergence of Complex Industries.Abstract

Labor informality, associated with low productivity and lack of access to social security services, dogs developing countries around the world. Rates of labor (in)formality, however, vary widely within countries. This paper presents a new stylized fact, namely the systematic positive relationship between the rate of labor formality and the working age population in cities. We hypothesize that this phenomenon occurs through the emergence of complex economic activities: as cities become larger, labor is allocated into increasingly complex industries as firms combine complementary capabilities derived from a more diverse pool of workers. Using data from Colombia, we use a network-based model to show that the technological proximity (derived from worker transitions between industry pairs) of current industries in a city to potential new complex industries governs the growth of the formal sector in the city. The mechanism proposed has robust strong predictive power, and fares better than alternative explanations of (in)formality.

Gomez-Lievano, A., Patterson-Lomba, O. & Hausmann, R., 2016. Explaining the Prevalence, Scaling and Variance of Urban Phenomena.Abstract

The prevalence of many urban phenomena changes systematically with population size1. We propose a theory that unifies models of economic complexity2, 3 and cultural evolution4 to derive urban scaling. The theory accounts for the difference in scaling exponents and average prevalence across phenomena, as well as the difference in the variance within phenomena across cities of similar size. The central ideas are that a number of necessary complementary factors must be simultaneously present for a phenomenon to occur, and that the diversity of factors is logarithmically related to population size. The model reveals that phenomena that require more factors will be less prevalent, scale more superlinearly and show larger variance across cities of similar size. The theory applies to data on education, employment, innovation, disease and crime, and it entails the ability to predict the prevalence of a phenomenon across cities, given information about the prevalence in a single city.

This paper is published in the journal, Nature: Human Behavior.

Explaining the prevalence, scaling and variance of urban phenomena
Gomez-Lievano, A., Patterson-Lomba, O. & Hausmann, R., 2016. Explaining the prevalence, scaling and variance of urban phenomena. Nature Human Behavior. Publisher's VersionAbstract

The prevalence of many urban phenomena changes systematically with population size1 . We propose a theory that unifies models of economic complexity2,3 and cultural evolution4 to derive urban scaling. The theory accounts for the difference in scaling exponents and average prevalence across phenomena, as well as the difference in the variance within phenomena across cities of similar size. The central ideas are that a number of necessary complementary factors must be simultaneously present for a phenomenon to occur, and that the diversity of factors is logarithmically related to population size. The model reveals that phenomena that require more factors will be less prevalent, scale more superlinearly and show larger variance across cities of similar size. The theory applies to data on education, employment, innovation, disease and crime, and it entails the ability to predict the prevalence of a phenomenon across cities, given information about the prevalence in a single city.

Related Content: The Urban Theory of Everything

Harvard Magazine: Recipes for Thriving Cities

Coscia, M., Hausmann, R. & Neffke, F., 2016. Exploring the Uncharted Export: An Analysis of Tourism-Related Foreign Expenditure with International Spend Data.Abstract

Tourism is one of the most important economic activities in the world: for many countries it represents the single largest product in their export basket. However, it is a product difficult to chart: "exporters" of tourism do not ship it abroad, but they welcome importers inside the country. Current research uses social accounting matrices and general equilibrium models, but the standard industry classifications they use make it hard to identify which domestic industries cater to foreign visitors. In this paper, we make use of open source data and of anonymized and aggregated transaction data giving us insights about the spend behavior of foreigners inside two countries, Colombia and the Netherlands, to inform our research. With this data, we are able to describe what constitutes the tourism sector, and to map the most attractive destinations for visitors. In particular, we find that countries might observe different geographical tourists' patterns - concentration versus decentralization -; we show the importance of distance, a country's reported wealth and cultural affinity in informing tourism; and we show the potential of combining open source data and anonymized and aggregated transaction data on foreign spend patterns in gaining insight as to the evolution of tourism from one year to another.

Diodato, D., Neffke, F. & O'Clery, N., 2016. Agglomeration Economies: The Heterogeneous Contribution of Human Capital and Value Chains.Abstract

**Updated version of this paper published here**

We document the heterogeneity across sectors in the impact labor and input-output links have on industry agglomeration. Exploiting the available degrees of freedom in coagglomeration patterns, we estimate the industry-specic benefits of sharing labor needs and supply links with local firms. On aggregate, coagglomeration patterns of services are at least as strongly driven by input-output linkages as those of manufacturing, whereas labor linkages are much more potent drivers of coagglomeration in services than in manufacturing. Moreover, the degree to which labor and input-output linkages are reflected in an industry's coagglomeration patterns is relevant for predicting patterns of city-industry employment growth.

Neffke, F., et al., 2014. Agents of Structural Change: The role of firms and entrepreneurs in regional diversification.Abstract

Who introduces structural change in regional economies: Entrepreneurs or existing firms? And do local or non‐local founders of establishments create most novelty in a region? Using matched employer/employee data for the whole Swedish workforce, we determine how unrelated and therefore how novel the activities of different establishments are to a region’s industry mix. Up‐ and downsizing establishments cause large shifts in the local industry structure, but these shifts only occasionally require an expansion of local capabilities because the new activities are often related to existing local activities. Indeed, these incumbents tend to align their production with the local economy, deepening the region’s specialization. In contrast, structural change mostly originates via new establishments, especially those with non‐local roots. Moreover, although entrepreneurs start businesses more often in activities unrelated to the existing regional economy, new establishments founded by existing firms survive in such activities more often, inducing longer‐lasting changes in the region.

Research Seminar Series

The Growth Lab's Research Seminar series is a weekly seminar that brings together researchers from across the academic spectrum who share an interest in growth and development. The seminar emphasizes interdisciplinary exchanges between the social and natural sciences, and speakers are welcome to present early-stage or mature work on a wide range of topics, including migration, local markets, structural change, innovation and the dynamics of technology, models of combinatorial growth, economic history, social and cultural evolution, the environmental impacts of growth, and trade.

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Neffke, F., Otto, A. & Hidalgo, C., 2016. The Mobility of Displaced Workers: How the Local Industry Mix Affects Job Search Strategies.Abstract

Establishment closures leave many workers unemployed. Based on employment histories of 20 million German workers, we find that workers often cope with their displacement by moving to different regions and industries. However, which of these coping strategies is chosen depends on the local industry mix. A large local presence of predisplacement or related industries strongly reduces the rate at which workers leave the region. Moreover, our findings suggest that a large local presence of the predisplacement industry induces workers to shift search efforts toward this industry, reducing the spatial scope of search for jobs in alternative industries and vice versa.

Coscia, M., Neffke, F. & Lora, E., 2015. Report on the Poblacion Flotante of Bogota.Abstract

In this document we describe the size of the Poblacion Flotante of
Bogota (D.C.). The Poblacion Flotante is composed by people who live
outside Bogota (D.C.), but who rely on the city for performing their job.
We estimate the Poblacion Flotante impact relying on a new data source
provided by telecommunications operators in Colombia, which enables us
to estimate how many people commute daily from every municipality of
Colombia to a specic area of Bogota (D.C.). We estimate that the size of
the Poblacion Flotante could represent a 5.4% increase of Bogota (D.C.)'s
population. During weekdays, the commuters tend to visit the city center
more.

Hausmann, R. & Neffke, F., 2016. The Workforce of Pioneer Plants.Abstract

Is labor mobility important in technological diffusion? We address this question by asking how plants assemble their workforce if they are industry pioneers in a location. By definition, these plants cannot hire local workers with industry experience. Using German social-security data, we find that such plants recruit workers from related industries from more distant regions and local workers from less-related industries. We also show that pioneers leverage a low-cost advantage in unskilled labor to compete with plants that are located in areas where the industry is more prevalent. Finally, whereas research on German reunification has often focused on the effects of east-west migration, we show that the opposite migration facilitated the industrial diversification of eastern Germany by giving access to experienced workers from western Germany.

Gomez-Lievano, A., Tellez, J. & Lora, E., 2015. New Insights About Wage Inequality in Colombia.Abstract

This paper presents a descriptive analysis of wage inequality in Colombia by cities and industries and attempts to evaluate the impact of the inequality of industries on inequality of cities. Using the 2010-2014 Colombian Social Security data, we calculate the gini coefficient for cities and industries and draw comparisons between their distributions. Our results show that while cities are unequal in similar ways, industries differ widely on how unequal they can be with ginis. Moreover, industrial structure plays a significant role to determine city inequality. Industrial framework proves to be a key element in this area for researches and policymakers.

Evidence That Calls-Based and Mobility Networks Are Isomorphic
Coscia, M. & Hausmann, R., 2015. Evidence That Calls-Based and Mobility Networks Are Isomorphic. PLOS One , 10. Publisher's VersionAbstract

Social relations involve both face-to-face interaction as well as telecommunications. We can observe the geography of phone calls and of the mobility of cell phones in space. These two phenomena can be described as networks of connections between different points in space. We use a dataset that includes billions of phone calls made in Colombia during a six-month period. We draw the two networks and find that the call-based network resembles a higher order aggregation of the mobility network and that both are isomorphic except for a higher spatial decay coefficient of the mobility network relative to the call-based network: when we discount distance effects on the call connections with the same decay observed for mobility connections, the two networks are virtually indistinguishable.

The network structure of economic output
Hausmann, R. & Hidalgo, C.A., 2011. The network structure of economic output. Journal of Economic Growth. Publisher's VersionAbstract

Much of the analysis of economic growth has focused on the study of aggregate output. Here, we deviate from this tradition and look instead at the structure of output embodied in the network connecting countries to the products that they export. We characterize this network using four structural features: the negative relationship between the diversification of a country and the average ubiquity of its exports, and the non-normal distributions for product ubiquity, country diversification and product co-export. We model the structure of the network by assuming that products require a large number of non-tradable inputs, or capabilities, and that countries differ in the completeness of the set of capabilities they have. We solve the model assuming that the probability that a country has a capability and that a product requires a capability are constant and calibrate it to the data to find that it accounts well for all of the network features except for the heterogeneity in the distribution of country diversification. In the light of the model, this is evidence of a large heterogeneity in the distribution of capabilities across countries. Finally, we show that the model implies that the increase in diversification that is expected from the accumulation of a small number of capabilities is small for countries that have a few of them and large for those with many. This implies that the forces that help drive divergence in product diversity increase with the complexity of the global economy when capabilities travel poorly.

Coscia, M., Hausmann, R. & Hidalgo, C.A., 2013. The Structure and Dynamics of International Development Assistance. Journal of Globalization and Development , 3 (2) , pp. 1-42. Publisher's VersionAbstract

We study the structure of international aid coordination by creating and analyzing a tripartite network of donor organizations, recipient countries and development issues using web-based information. We develop a measure of coordination and find that it is moderate, achieving about 60% of its theoretical maximum. Many countries are strongly connected to organizations that are related to the issues that are salient there. Nevertheless, we identify many countries that are poorly served, issues that are inadequately attended to, and organizations that focus on the wrong combination of places and issues. Our approach may be used to improve decentralized coordination.

Hausmann, R. & Klinger, B., 2006. Structural Transformation and Patterns of Comparative Advantage in the Product Space.Abstract

In this paper we examine the product space and its consequences for the process of structural transformation. We argue that the assets and capabilities needed to produce one good are imperfect substitutes for those needed to produce other goods, but the degree of asset specificity varies widely. Given this, the speed of structural transformation will depend on the density of the product space near the area where each country has developed its comparative advantage. While this space is traditionally assumed to be smooth and continuous, we find that in fact it is very heterogeneous, with some areas being very dense and others quite sparse. We develop a measure of revealed proximity between products using comparative advantage in order to map this space, and then show that its heterogeneity is not without consequence. The speed at which countries can transform their productive structure and upgrade their exports depends on having a path to nearby goods that are increasingly of higher value.

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