Knowledge that Transforms

Analysis of daily reported incidents of major crimes in twelve U.S. cities reveals an increase in crime over the course of monthly welfare payment cycles. This increase reflects an increase in crimes that are likely to have a direct financial motivation as opposed to other kinds of crime. Temporal patterns in crime are observed in jurisdictions in which disbursements are focused at the beginning of monthly welfare payment cycles and not in jurisdictions in which disbursements are relatively more staggered. These findings indicate that welfare beneficiaries consume welfare-related income quickly and then attempt to supplement it with criminal income.

Using data for six Asian miracle economies over the period from 1953 to 2006, this paper examines the extent to which growth has been driven by R&D and tests which second-generation endogenous growth model is most consistent with the data. The results give strong support to Schumpeterian growth theory but only limited support to semi-endogenous growth theory. Furthermore, it is shown that R&D has played a key role for growth in the Asian miracle economies.

Employing droughts and floods to proxy for changes in precipitation, this paper shows nomadic incursions into settled Han Chinese regions over a period of more than two thousand years—the most enduring clash of civilizations in history—to be positively correlated with less rainfall and negatively correlated with more rainfall. Consistent with findings that economic shocks are positively correlated with conflicts in modern sub-Saharan Africa when instrumented by rainfall, our reduced-form results extend this relationship to a very different temporal and geographical context, the Asian continent, and long historical period.

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.