Knowledge that Transforms

We build a new concordance between the NBER Patent Data and U.S. Census microdata and use it to examine what happens when firms patent. We find strong evidence that increases in patent stock are associated with increases in firm size, scope, and skill and capital intensity. We find somewhat weaker evidence that changes in patenting are positively correlated with changes in total factor productivity. We also analyze first-time patentees and find similar effects following initial patent application. Together, these results suggest that patenting is indeed associated with real changes within firms, in particular with growth through increases in scope.

Over the past several decades, the HIV/AIDS epidemic has dramatically altered patterns of morbidity and mortality in sub-Saharan Africa, with potential consequences for human capital investment and economic growth. Using data from Demographic and Health Surveys for fifteen countries in sub-Saharan Africa, I estimate the relationship between regional HIV prevalence and the change in individual human capital investment over time. Consistent with a simple model of human capital investment incorporating mortality risk, I find that areas with higher levels of HIV experienced relatively larger declines in schooling.

The main reason governments grant patent protection is to spur innovation. However, the size of the R&D stimulus from patent protection is far from clear because it depends on how effective patents are as a mechanism for appropriating returns. Drawing on real options investment theory, this paper highlights one mechanism through which patents may improve appropriability and stimulate R&D investment: patents reduce the effect of market uncertainty on the firm’s investment decision. We find that firm-level R&D investment falls in response to higher levels of uncertainty, but that patent protection partially mitigates the influence of uncertainty.

This paper examines the extent to which Mexican emigrants to the United States are negatively selected. Previous studies have been limited by the lack of nationally representative longitudinal data. This one uses a newly available household survey, that identifies emigrants before they leave. On average, U.S.-bound Mexican emigrants from 2000 to 2004 earn lower wages and have less (more for females) schooling than nonmigrant Mexicans, evidence of negative selection. This argues against Chiquiar and Hanson's (2005) findings. The discrepancy is primarily due to an undercount of unskilled migrants in U.S. sources and secondarily to the omission of unobservables in their methodology.

We use a migration lottery program to overcome the double-selectivity problems posed by migration. We compare a wide range of outcomes for the remaining household members of Tongan emigrants with those of members of similar households who were unsuccessful in the lottery, with the policy rules determining which household members can move. Multiple hypothesis testing procedures are used to examine robustness. The overall impact on households left behind is largely negative in terms of resource availability, and both sources of selectivity matter, leading studies that fail to address them adequately to misrepresent the impact of migration on households.

This paper uses restricted census microdata to examine housing values and rents for neighborhoods in the United States where power plants were opened during the 1990s. Compared to neighborhoods with similar housing and demographic characteristics, neighborhoods within 2 miles of plants experienced 3%–7% decreases in housing values and rents, with some evidence of larger decreases within 1 mile and for large-capacity plants. In addition, there is evidence of taste-based sorting, with neighborhoods near plants associated with modest but statistically significant decreases in mean household income, educational attainment, and the proportion owner-occupied.

Using firm-level data collected by the U.S. Bureau of Economic Analysis, we estimate the impact on U.S. manufacturing employment of changes in foreign affiliate wages. We show that the motive for offshoring and, consequently, the location of offshore activity, significantly affects the impact of offshoring on parent employment. In general, offshoring to low-wage countries substitutes for domestic employment. However, for firms that do significantly different tasks at home and abroad, foreign and domestic employment are complements. These offsetting effects may be combined to show that offshoring by U.S.-based multinationals is associated with a quantitatively small decline in manufacturing employment.

Using 1980–2000 Census data to study the impact of source country characteristics on married adult immigrants' labor supply assimilation profiles, we find that immigrant women from countries with high female labor supply persistently work more than those from low-female-supply countries. While both groups of women work less than comparable natives on arrival, women from high-female-participation countries eventually close the gap with natives entirely, and women from low-female-labor supply countries eliminate most of it. Men's labor supply is unaffected by source country female participation, suggesting that the findings on women reflect notions of gender roles.

Prevailing measures of relative poverty are unchanged when all incomes grow or contract by the same proportion. This property stems from seemingly implausible assumptions about the disutility of relative deprivation and the cost of social inclusion. We propose “weakly relative” lines that relax these assumptions. On calibrating our measures to national poverty lines and survey data, we find that half the population of the developing world in 2005 lived in poverty, only half of whom were absolutely poor. The total number of poor rose over 1981 to 2005 despite falling numbers of absolutely poor. With sustained economic growth, the incidence of relative poverty became less responsive to further growth. The number of relatively poor rose, just as the numbers of absolutely poor fell.

Using multiple data sets from different time periods, we document declines in academic time investment by full-time college students in the United States between 1961 and 2003. Full-time students allocated 40 hours per week toward class and studying in 1961, whereas by 2003, they were investing about 27 hours per week. Declines were extremely broad based and are not easily accounted for by framing effects, work or major choices, or compositional changes in students or schools. We conclude that there have been substantial changes over time in the quantity or manner of human capital production on college campuses.