David Weil - Academia.edu (original) (raw)

Papers by David Weil

Social Science Research Network, 2019

The Policy Research Working Paper Series disseminates the findings of work in progress to encoura... more The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent.

Quality-adjusted population density (QAPD) is population divided by land area that has been adjus... more Quality-adjusted population density (QAPD) is population divided by land area that has been adjusted for geographic characteristics. We derive weights on these geographic characteristics from a global regression of population density at the quarter-degree level with country fixed effects. We show, first, that while income per capita is uncorrelated with conventionally measured population density across countries, there is a strong negative correlation between income per capita and QAPD; second, that the magnitude of this relationship exceeds the plausible structural effect of density on income, suggesting a negative correlation between QAPD and productivity or factor accumulation; and third, that higher QAPD in poor countries is primarily due to population growth since 1820. We argue that these facts are best understood as results of the differential timings of economic takeoff and demographic transition across countries, and particularly the rapid transfer of health technologies fr...

California for assistance with the Future Elderly Model simulations. The views expressed herein a... more California for assistance with the Future Elderly Model simulations. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. At least one co-author has disclosed a financial relationship of potential relevance for this research. Further information is available online at http://www.nber.org/papers/w23329.ack NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

and a research associate of the National Bureau of Economic Research. For acknowledgments, source... more and a research associate of the National Bureau of Economic Research. For acknowledgments, sources of research support, and disclosure of the authors' material financial relationships, if any, please see http:// www .nber .org/ chapters/ c13386.ack. 1. Africa's disappointing growth between 1960 and 2000 is the subject of a two-volume work (see Ndulu et al. 2008).

The Quarterly Journal of Economics, 2010

for valuable research assistance. The views expressed herein are those of the author(s) and do no... more for valuable research assistance. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

The Quarterly Journal of Economics, 2007

I use microeconomic estimates of the effect of health on individual outcomes to construct macroec... more I use microeconomic estimates of the effect of health on individual outcomes to construct macroeconomic estimates of the proximate effect of health on GDP per capita. I employ a variety of methods to construct estimates of the return to health, which I combine with crosscountry and historical data on height, adult survival rates, and age at menarche. Using my preferred estimate, eliminating health differences among countries would reduce the variance of log GDP per worker by 9.9 percent and reduce the ratio of GDP per worker at the 90th percentile to GDP per worker at the 10th percentile from 20.5 to 17.9. While this effect is economically significant, it is also substantially smaller than estimates of the effect of health on economic growth that are derived from crosscountry regressions.

Carnegie-Rochester Conference Series on Public Policy, 1994

We examine the relationship between income growth and saving using both crosscountry and househol... more We examine the relationship between income growth and saving using both crosscountry and household data. At the aggregate level, we find that growth Granger causes saving, but saving does not Granger cause growth. Using household data, we find that households with predictably higher income growth save more than households with predictably low growth. We argue that standard permanent income models of consumption cannot explain these findings, but, a model of consumption with habit formation may. The positive effect of growth on saving implies that previous estimates of the effect of saving on growth may be overstated.

Journal of Development Economics, 2000

We examine the role of increased life expectancy in raising human capital investment during the p... more We examine the role of increased life expectancy in raising human capital investment during the process of economic growth. We develop a continuous time, overlapping generations model in which individuals make optimal schooling investment choices in the face of a constant probability of death. We present analytic results, followed by results from a calibrated version of the model using realistic estimates of the return to schooling. Mortality decline produces economically significant increases in schooling and consumption. Allowing schooling to vary endogenously produces a much larger response of consumption and capital to mortality decline than is observed when schooling is held fixed.

Iodine deficiency is the leading cause of preventable mental retardation in the world today. Iodi... more Iodine deficiency is the leading cause of preventable mental retardation in the world today. Iodine deficiency was common in the developed world until the introduction of iodized salt in the 1920's. The incidence of iodine deficiency is connected to low iodine levels in the soil and water. We examine the impact of salt iodization in the US by taking advantage of this natural geographic variation. Areas with high pre-treatment levels of iodine deficiency provide a treatment group which we can compare to a control group of low iodine deficiency areas. In the US, salt was iodized over a very short period of time around 1924. We use previously unused data collected during WWI and WWII to compare outcomes of cohorts born before and after iodization, in localities that were naturally poor and rich in iodine. We find evidence of the beneficial effects of iodization on the cognitive abilities of the cohorts exposed to it.

aeaweb.org

From 1935 to 1963 a malaria eradication campaign in Sri Lanka reduced incidence from 97% of the p... more From 1935 to 1963 a malaria eradication campaign in Sri Lanka reduced incidence from 97% of the population to 17 cases. This paper combines this exogenous malaria eradication campaign and the preexisting heterogenous malaria levels in Sri Lanka with two household surveys to identify the e¤ect of malaria eradication on fertility, survival, and human capital accumulation across two successive generations. Contrary to theories of the demographic transition, a movement along the quantity-quality trade-o¤, and sequential or replacement fertility, the initial e¤ect of malaria eradication was an increase in fertility. To separate the direct health e¤ects from other potential causes of the increase in fertility, I exploit the particular epidemiology of malaria: the symptoms are more severe for primigravidae, women pregnant for the …rst time, than for multigravidae, women of higher order parity. Since malaria eradication induced a larger increase in survival probabilities for …rst born children and quickened the transition to initial parity while the transition time to higher order parity did not change, I conclude that the source of the increase in fertility was the elimination of the biological constraint. In the second generation, those born after eradication in the previously most heavily infected regions accumulate more human capital as measured by years of education or literacy. They also have lower fertility. Therefore, while the initial population growth might be detrimental to GDP per capita, increased education and lower subsequent fertility can mitigate this initial negative growth e¤ect.

The Quarterly Journal of Economics

We explore the role of natural characteristics in determining the worldwide spatial distribution ... more We explore the role of natural characteristics in determining the worldwide spatial distribution of economic activity, as proxied by lights at night, observed across 240,000 grid cells. A parsimonious set of 24 physical geography attributes explains 47% of worldwide variation and 35% of within-country variation in lights. We divide geographic characteristics into two groups, those primarily important for agriculture and those primarily important for trade, and confront a puzzle. In examining within-country variation in lights, among countries that developed early, agricultural variables incrementally explain over 6 times as much variation in lights as do trade variables, while among late developing countries the ratio is only about 1.5, even though the latter group is far more dependent on agriculture. Correspondingly, the marginal effects of agricultural variables as a group on lights are larger in absolute value, and those for trade smaller, for early developers than for late deve...

Policy Research Working Papers

Journal of Demographic Economics

I examine recent changes in African mortality and discuss their potential economic and demographi... more I examine recent changes in African mortality and discuss their potential economic and demographic effects. Growth in life expectancy sharply departed from its trend after 1990, and then experienced a sharp acceleration after 2005. This latter acceleration was due overwhelmingly to improvements in HIV and malaria. Economists differ in their estimates of how large the structural effect of health on income is, with many estimates being relatively small. Taking seriously the delays built into many plausible causal channels would lead one to expect that any economic effects of these mortality changes, if they are detectable at all, will not appear for several decades. By contrast, the effect of declining mortality, especially from malaria, should soon be visible in data on population age structure in some countries.

Research in Economics

As populations age, the degree to which workers' human capital reflects the cutting edge of techn... more As populations age, the degree to which workers' human capital reflects the cutting edge of technology falls because education took place further in the past. This "pure vintage" effect of aging is well known. In this paper, we explore a second effect of aging: In an older population, older teachers pass on knowledge that was current further in the past. We show that this "teacher multiplier" can significantly increase the technological backwardness of the labor force. We present both an analytic model that can be solved for steady states and a numerical model that can describe transitions in the average vintage of human capital as population age structure changes over time. We also discuss evidence on the effect of age on the technological up-to-dateness of workers in general and teachers in particular.

Journal of Economic Literature, 2015

This book explores the relationship between the material standard of living and health, both acro... more This book explores the relationship between the material standard of living and health, both across countries and over time. Above all, Deaton is interested in the question of whether income growth contributes significantly to better health. His answer is no: saving lives in poor countries is not expensive, and there are many episodes of massive health improvements in the absence of income growth. As an alternative, he argues that the cross-sectional correlation between health and income is induced by variation in institutional quality, while over time, parallel improvements in income and health have been a result of advancing knowledge. (JEL E23, I12, I14, I15, O15, O47)

American Economic Review, 2013

We study the mobile phone-based money transfer system in Kenya. Based on aggregate data, we estim... more We study the mobile phone-based money transfer system in Kenya. Based on aggregate data, we estimate that the velocity with which units of e-money are transferred among users is approximately four times per month, and that the average number of transfers undergone by a unit of e-money between its creation and destruction is approximately one. Most M-Pesa transactions are made by frequent users. Examination of data on withdrawals shows a high frequency of small withdrawals and no response to “notches” in the price schedule, indicating that many users seem to have high implicit discount rates.

for helpful comments. The views expressed herein are those of the authors and do not necessarily ... more for helpful comments. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.