J. Vernon Henderson

Bio: J. Vernon Henderson is an academic researcher from London School of Economics and Political Science. The author has contributed to research in topics: Population & Urbanization. The author has an hindex of 64, co-authored 178 publications receiving 21137 citations. Previous affiliations of J. Vernon Henderson include National Bureau of Economic Research & University of Connecticut.

Industrial Development in Cities

Abstract: Using extensive data on 1970 and 1987 urban characteristics, the paper analyzes changes in employment in specific manufacturing industries in cities between 1970 and 1987. Two sets of questions are the focus. First, what present or past characteristics of a city's economic environment are critical in determining current employment levels in different industries? How much persistence in employment patterns is there over time and what is the source of that persistence? The second set of questions explores what inferences can be made from the data and results concerning the nature of externalities in urban markets, involving diversity of suppliers to firms, information spillovers concerning current market conditions and information spillovers involving the spread of technology. While the literature assumes employment levels in individual industries in individual cities show strong mean reversion ("convergence"), in fact that is not the case in the 1970-87 time period. The raw data show strong persistence. The major source of that persistence appears to be persistence in local demand conditions (i.e., persistence in regional comparative advantage), as opposed to other measured or unmeasured urban characteristics. Retention of employment is also strongly helped by the historical degree of local specialization in the industry, perhaps indicating a form of dynamic externality. Other historical conditions are not important.

Measuring Economic Growth from Outer Space

Abstract: GDP growth is often measured poorly for countries and rarely measured at all for cities or subnational regions. We propose a readily available proxy: satellite data on lights at night. We develop a statistical framework that uses lights growth to augment existing income growth measures, under the assumption that measurement error in using observed light as an indicator of income is uncorrelated with measurement error in national income accounts. For countries with good national income accounts data, information on growth of lights is of marginal value in estimating the true growth rate of income, while for countries with the worst national income accounts, the optimal estimate of true income growth is a composite with roughly equal weights. Among poor-data countries, our new estimate of average annual growth differs by as much as 3 percentage points from official data. Lights data also allow for measurement of income growth in sub- and supranational regions. As an application, we examine growth in Sub Saharan African regions over the last 17 years. We find that real incomes in non-coastal areas have grown faster by 1/3 of an annual percentage point than coastal areas; non-malarial areas have grown faster than malarial ones by 1/3 to 2/3 annual percent points; and primate city regions have grown no faster than hinterland areas. Such applications point toward a research program in which "empirical growth" need no longer be synonymous with "national income accounts."

Industrial Development in Cities

Abstract: This paper uses data for eight manufacturing industries in 1970 and 1987 to test for and characterize dynamic production externalities in cities. We find evidence of both MAR externalities, which are associated with past own industry employment concentration, and Jacobs externalities, which are associated with past diversity of local total employment. More specifically, for mature capital goods industries, there is evidence of MAR externalities but none of Jacobs externalities. For new high-tech industries, there is evidence of Jacobs and MAR externalities. These findings are consistent with notions of urban specialization and product cycles: new industries prosper in large, diverse metropolitan areas, but with maturity, production decentralizes to smaller, more specialized cities. For mature industries, there is also a high degree of persistence in individual employment patterns across cities, fostered by both MAR externalities and persistence in regional comparative advantage.

Measuring Economic Growth from Outer Space

Abstract: GDP growth is often measured poorly for countries and rarely measured at all for cities or subnational regions. We propose a readily available proxy: satellite data on lights at night. We develop a statistical framework that uses lights growth to augment existing income growth measures, under the assumption that measurement error in using observed light as an indicator of income is uncorrelated with measurement error in national income accounts. For countries with good national income accounts data, information on growth of lights is of marginal value in estimating the true growth rate of income, while for countries with the worst national income accounts, the optimal estimate of true income growth is a composite with roughly equal weights. Among poor-data countries, our new estimate of average annual growth differs by as much as 3 percentage points from official data. Lights data also allow for measurement of income growth in sub- and supranational regions. As an application, we examine growth in Sub Saharan African regions over the last 17 years. We find that real incomes in non-coastal areas have grown faster by 1/3 of an annual percentage point than coastal areas; non-malarial areas have grown faster than malarial ones by 1/3 to 2/3 annual percent points; and primate city regions have grown no faster than hinterland areas. Such applications point toward a research program in which "empirical growth" need no longer be synonymous with "national income accounts."

Marshall's Scale Economies

Abstract: In this paper, using panel data, I estimate plant level production functions that include variables that allow for two types of scale externalities which plants experie nce in their local industrial environments. First are externalities from other plants in the same industry locally, usually called localization economies or, in a dynamic context, Marshall, Arrow, Romer [MAR] economies. Second are externalities from the scale or diversity of local economic activity outside the own industry involving some type of cross- fertilization, usually called urbanization economies or, in a dynamic context, Jacobs economies. Estimating production functions for plants in high tech industries and in capital goods, or machinery industries, I find that local own industry scale externalities, as measured specifically by the count of other own industry plants locally, have strong productivity effects in high tech but not machinery industries. I find evidence that single plant firms both benefit more from and generate greater external benefits than corporate plants. On timing, I find evidence that high tech single plant firms benefit from the scale of past own industry activity, as well as current activity. I find no evidence of urbanization economies from the diversity of local economic activity outside the own industry and limited evidence of urbanization economies from the overall scale of local economic activity.

Growth in Cities

Abstract: Recent theories of economic growth, including Romer (1986), Porter (1989) and Jacobs (1969), have stressed the role of technological spillovers in generating growth. Because such knowledge spillovers are particularly effective in cities, where communication between people is more extensive, data on the growth of industries in different cities allows us to test some of these theories. Using a new data set on the growth of large industries in 170 U.S. cities between 1956 and 1987, we find that local competition and urban variety, but not regional specialization, encourage employment growth in industries. The evidence suggests that important knowledge spillovers might be between, rather than within industries, consistent with the theories of Jacobs (1969).

Growth in Cities

Abstract: Recent theories of economic growth, including those of Romer, Porter, and Jacobs, have stressed the role of technological spillovers in generating growth. Because such knowledge spillovers are particularly effective in cities, where communication between people is more extensive, data on the growth of industries in different cities allow us to test some of these theories. Using a new data set on the growth of large industries in 170 U.S. cities between 1956 and 1987, we find that local competition and urban variety, but not regional specialization, encourage employment growth in industries. The evidence suggests that important knowledge spillovers might occur between rather than within industries, consistent with the theories of Jacobs.

Climate change 2014 - Mitigation of climate change

Abstract: The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

Abstract: We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.