Knowledge that Transforms

Most Americans are now in some form of managed care plan that restricts access to services in order to reduce costs. It is difficult to determine whether these restrictions affect health because individuals and firms self-select into managed care. We investigate the effect of managed care using a California law that required some pregnant women on Medicaid to enter managed care. We use a unique longitudinal database of California births in which we observe changes in the regime faced by individual mothers between births. We find that Medicaid managed care reduced the quality of prenatal care and increased low birth weight, prematurity, and neonatal death.

In 2000, a genetically modified corn variety called StarLink that was not approved for human consumption was discovered in the food-corn supply. To estimate the price impact of this event on the U.S. corn market, we develop the relative price of a substitute method. This method applies not only to the StarLink event but also to rare events in other markets. We find that the contamination led to a 6.8% discount in corn prices and that the suppression of prices lasted for at least a year.

Recent empirical evidence demonstrates the presence of an important long-memory component in realized asset return volatility. We specify and estimate multivariate models for the joint dynamics of stock returns and volatility that allow for long memory in volatility without imposing this property on returns. Asset pricing theory imposes testable cross-equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short lived, in spite of a positive risk-return tradeoff and long memory in volatility.

We develop an econometric model where the determinants of working while in school, academic performance, and the decision to drop out are set in the context of two types of high school students: those who prefer schooling and those who are more likely to join the labor market. The likelihood function of this model with heterogeneous preferences for schooling is composed of 48 individual contributions of a standard quadrivariate normal function. Exploiting a unique Canadian microdata set of high school students and school dropouts, we show that being a female student, attending a private school, and living with educated parents are linked to having a strong preference for schooling over the labor market. We also find that working fewer than fifteen hours per week while in school is not necessarily detrimental to success in school. Our results indicate that the decision to drop out is affected by the legal age to access the labor market, high minimum wages, and low unemployment rates. Several policies that aim at reducing the number of high school dropouts are identified.

Merger control authorities may approve a merger based on an “efficiency defense.” An important aspect in clearing mergers is that the efficiencies need to be merger-specific. Joint ventures, and in particular research joint ventures (RJVs), may achieve comparable efficiencies possibly without the anticompetitive (market power) effects of mergers. We empirically account for the endogenous formation of mergers and RJVs and provide evidence that at the semiconductor level, mergers and RJVs achieve dominant (net) efficiency effects. Our counterfactuals provide evidence that the efficiency gains caused by mergers would have been achieved by RJVs as well. Therefore, RJVs often represent viable alternatives to mergers from the consumer welfare point of view. At the more disaggregate level we find that the efficiency effects are larger in the microcomponents than in the memory market. This finding emphasizes the importance of market determinants (such as product differentiation and entry) having an impact on efficiency and market power effects.

We use administrative data from Missouri to examine the sensitivity of earnings impact estimates for a job training program based on alternative nonexperimental methods. We consider regression adjustment, Mahalanobis distance matching, and various methods using propensity-score matching, examining both cross-sectional estimates and difference-in-difference estimates. Specification tests suggest that the difference-in-difference estimator may provide a better measure of program impact. We find that propensity-score matching is most effective, but the detailed implementation is not of critical importance. Our analyses demonstrate that existing data can be used to obtain useful estimates of program impact.

The World Health Organization estimates that 300 million clinical cases of malaria occur annually and observed that during the 80s and part of the 90s its incidence increased. In this paper, we explore the influence of refugees from civil wars on the incidence of malaria in the refugee-receiving countries. Using civil wars as an instrumental variable, we show that for each 1,000 refugees there are between 2,000 and 2,700 cases of malaria in the refugee-receiving country. On average 13% of the cases of malaria reported by the WHO are caused by forced migration as a consequence of civil wars.

The impact of candidate campaign spending on votes and abstention in multiparty elections is estimated from the specification of a structural model of voter behavior. This model accounts for the endogeneity of campaign spending as well as the heterogeneity in voter preferences. Empirical results are estimated from aggregate (actual) election data. The results demonstrate the importance of spending during the campaign period and voter heterogeneity with respect to these expenditures. The own- and cross-expenditure vote share elasticity estimates reveal that political campaign spending not only redistributes voters across parties but also decreases the size of the abstaining group of the electorate.

We assess competition among retail depository institutions in 1,884 rural markets. We estimate an equilibrium market structure model that endogenizes the operating decisions of three types of depository institutions: multimarket banks, single-market banks, and thrift institutions. Observed market structures and a game-theoretic specification of entry behavior identify the parameters of an underlying profit function. We find strong evidence that product differentiation generates additional profits for retail depository institutions. These profits help to maintain smaller banks and thrifts, even as larger banks expand their operations. Consumers have more options, as more institutions can profitably operate as a result of product differentiation.

This paper estimates the agglomeration benefits that arise from vertical linkages between firms in the context of Indonesia. The analysis is based on international trade and economic geography theory developed by Krugman and Venables (1995). We identify the agglomeration benefits off the spatial variation in firm level nominal wages. Unusually detailed intermediate input data allow us to more accurately capture spatial input/output linkages than in previous studies. We take account of the location of input suppliers to estimate cost linkages; and the location of demand from final consumers and other firms to estimate demand linkages. The results show that the externalities that arise from demand and cost linkages are quantitatively important and highly localized. An understanding of the extent and strength of spatial linkages is crucial in shaping policies that seek to influence regional development.