Knowledge that Transforms

This paper explores the impact of the introduction of the widely viewed MTV reality show 16 and Pregnant on teen childbearing. Our main analysis relates geographic variation in changes in teen childbearing rates to viewership of the show. We implement an instrumental variables (IV ) strategy using local area MTV ratings data from a pre-period to predict local area 16 and Pregnant ratings. The results imply that this show led to a 4.3 percent reduction in teen births. An examination of Google Trends and Twitter data suggest that the show led to increased interest in contraceptive use and abortion.

This paper argues that the extent of financial contagion exhibits a form of phase transition: as long as the magnitude of negative shocks affecting financial institutions are sufficiently small, a more densely connected financial network (corresponding to a more diversified pattern of interbank liabilities) enhances financial stability. However, beyond a certain point, dense interconnections serve as a mechanism for the propagation of shocks, leading to a more fragile financial system. Our results thus highlight that the same factors that contribute to resilience under certain conditions may function as significant sources of systemic risk under others.

This paper uses an assignment model to understand the cross section of house prices within a metro area. Movers’ demand for housing is derived from a life-cycle problem with credit market frictions. Equilibrium house prices adjust to assign houses that differ by quality to movers who differ by age, income, and wealth. To quantify the model, we measure distributions of house prices, house qualities, and mover characteristics from micro-data on San Diego County during the 2000s boom. The main result is that cheaper credit for poor households was a major driver of prices, especially at the low end of the market.

This paper uses a unique and rich administrative data set to analyze the impact of the introduction of a new grading policy on graduations rates at Benedict College, a Historically Black College in Columbia, South Carolina. According to the new grading policy, grades for underclassmen are determined in part by performance on tests and in part by measures of “effort” such as attendance and class participation. This paper finds that while graduates graduate at a faster rate under the policy, there is no significant difference between graduation rates before and after the policy was implemented.

High rates of customer default on utility bills present a barrier to the expansion of electricity access in the developing world. Pre-paid electricity metering offers a technological solution to ensuring timely payment. Using an eleven-year panel of pre-paid electricity customers in Cape Town, South Africa, we describe patterns of purchase behavior across property values, our measure of socioeconomic status. Poorer households buy electricity more often, in smaller increments, and are most likely to buy on payday. These patterns suggest difficulties smoothing income, and reveal a preference for small, frequent purchases that is incompatible with a standard monthly electricity billing cycle.

This paper describes a growth model with the property that human capital accumulation can account for all observed growth. The model is shown to be consistent with evidence on individual productivities as measured by census earnings data. The central hypothesis is that we learn more when we interact with more productive people.

We pose good markets frictions on top of an otherwise standard two-country international real business cycle (IRBC) model. Shopping for goods takes effort, which prevents perfect matching between customers and producers. An increase in search effort implies increased measured productivity. Demand shocks increase expenditures and search effort simultaneously increasing output, consumption, productivity, and the trade deficit and appreciating the real exchange rate. Thus we solve the Backus-Smith puzzle and we show that the cross country correlation of consumption is higher than that of output. Standard IRBC models cannot account for these puzzles along with movements in TFP.

This paper studies the impact of an R&D cost shock on R&D investments, imported inputs, and their joint impact on firm performance. We introduce imported inputs into a model of R&D and endogenous productivity, and show that R&D and international sourcing are complementary activities. Exploiting the introduction of an R&D tax credit in Norway in 2002, we find that cheaper R&D stimulated not only R&D investments but also imports of intermediates, quantitatively consistent with the model. An implication of our work is that improved access to imported inputs promotes R&D investments and, ultimately, technological change.

This paper documents the existence and characteristics of US firms that do not manufacture themselves, but nonetheless are heavily involved in the production of goods. These factoryless goods producing firms (FGPFs) are formally in the wholesale sector but, unlike traditional wholesale firms, FGPFs design the goods they sell and coordinate production activities. FGPFs in the wholesale sector are larger and younger, pay higher wages, span more sectors and had more manufacturing employment in previous years compared to traditional wholesalers. FGPFs are more likely to import than typical wholesalers, though their imports constitute a smaller share of their total domestic activity.

We develop a model of selection that incorporates a key element of recent health reforms: an individual mandate. Using data from Massachusetts, we estimate the parameters of the model. In the individual market for health insurance, we find that premiums and average costs decreased significantly in response to the individual mandate. We find an annual welfare gain of 4.1% per person or $51.1 million annually in Massachusetts as a result of the reduction in adverse selection. We also find smaller post-reform markups.