Knowledge that Transforms

This paper addresses microeconometric evaluation by matching methods when the programs under consideration are heterogeneous. Assuming that selection into the different subprograms and the potential outcomes are independent given observable characteristics, estimators based on different propensity scores are compared and applied to the analysis of active labor market policies in the Swiss region of Zurich. Furthermore, the issues of heterogeneous effects and aggregation are addressed. The results suggest that an approach that incorporates the possibility of having multiple programs can be an informative tool in applied work.

This paper estimates the effect of changing environmental standards on patterns of international investment. The analysis advances the existing literature in three ways. First, we avoid comparing different countries by examining foreign direct investment in the United States and differences in pollution abatement costs among U.S. states. Data on environmental costs in U.S. states are more comparable than those for different countries, and U.S. states are more similar in other difficult-to-measure dimensions. Second, we allow for differences in states' industrial compositions, an acknowledged problem for earlier studies. Third, we employ an 18-year panel of relative abatement costs, allowing us to control for unobserved state characteristics. We find robust evidence that abatement costs have had moderate deterrent effects on foreign investment.

The labor market prospects of young, unskilled men fell dramatically in the 1980s and improved in the 1990s. Crime rates show a reverse pattern: increasing during the 1980s and falling in the 1990s. Because young, unskilled men commit most crime, this paper seeks to establish a causal relationship between the two trends. Previous work on the relationship between labor markets and crime focused mainly on the relationship between the unemployment rate and crime, and found inconclusive results. In contrast, this paper examines the impact of both wages and unemployment on crime, and uses instrumental variables to establish causality. We conclude that both wages and unemployment are significantly related to crime, but that wages played a larger role in the crime trends over the last few decades. These results are robust to the inclusion of deterrence variables, controls for simultaneity, and controlling for individual and family characteristics.

Corruption and imperfect contract enforcement dramatically reduce international trade. This paper estimates the reduction using a structural model of import demand in which insecurity acts as a hidden tax on trade. We find that inadequate institutions constrain trade as much as tariffs do. We also find that omission of indices of institutional quality biases the estimates of typical gravity models, obscuring a negative relationship between per capita income and the share of total expenditure devoted to traded goods. Finally, we argue that cross-country variation in the effectiveness of institutions and the consequent variation in the prices of traded goods offer a simple explanation for the stylized fact that high-income, capital-abundant countries trade disproportionately with each other.

This paper examines the long-standing theory that the growth of small firms is often constrained by the quantity of internal finance. Under plausible assumptions, when financing constraints are binding, an additional dollar of internal finance should generate slightly more than an additional dollar of growth in assets. This quantitative prediction should not hold for the relatively small number of firms which access external equity. We test these predictions with a panel of more than 1, 600 small firms and find that the growth of most firms is constrained by internal finance. Our results have implications for several different research literatures, including models of firm growth.

This paper studies how the Hodrick-Prescott filter should be adjusted when changing the frequency of observations. It complements the results of Baxter and King (1999) with an analytical analysis, demonstrating that the filter parameter should be adjusted by multiplying it with the fourth power of the observation frequency ratios. This yields an HP parameter value of 6.25 for annual data given a value of 1600 for quarterly data. The relevance of the suggestion is illustrated empirically.

This paper considers causal inference and sample selection bias in nonexperimental settings in which (i) few units in the nonexperimental comparison group are comparable to the treatment units, and (ii) selecting a subset of comparison units similar to the treatment units is difficult because units must be compared across a high-dimensional set of pre-treatment characteristics. We discuss the use of propensity score-matching methods, and implement them using data from the National Supported Work experiment. Following LaLonde (1986), we pair the experimental treated units with nonexperimental comparison units from the CPS and PSID, and compare the estimates of the treatment effect obtained using our methods to the benchmark results from the experiment. For both comparison groups, we show that the methods succeed in focusing attention on the small subset of the comparison units comparable to the treated units and, hence, in alleviating the bias due to systematic differences between the treated and comparison units.