Long-duration employment opportunities are a necessary condition for workers to hold lifetime jobs. This paper uses longitudinal data on individual U.S. manufacturing plants from 1963-1982 to estimate the age and completed spell distributions for employment positions. The results indicate that, of the employment opportunities in progress in the U.S. manufacturing sector in 1982, 30.0% were at least 19 years old and 59.6% would have a completed length of at least 20 years. High rates of turnover in employment positions coexist with a large number of long-duration employment opportunities because the turnover tends to be concentrated within a subset of the producers.

This paper examines the relationship among U.S. imports from the NICs, imports from developed countries, capital, and labor in the production of goods for final demand. Import demand and substitution elasticities are estimated for the period 1960-80. U.S. imports from the NICs are found to be complements with both labor and imports from industrialized countries. This indicates that the substitution effect resulting from a reduction in the price of imports from the NICs would lead to a net increase in employment. Multilateral tariff cuts by the United States would increase the demand for NIC goods despite a reduction in their preferential tariff margins.

Environmental regulations set maximum allowable rates for sulfur dioxide emissions from electric utilities. By ignoring firm differences in marginal abatement costs and preventing emissions trading, these standards do not minimize the cost of reducing einissions. This paper estimates marginal abatement cost functions for 56 utilities for 1973-79. Marginal costs vary substantially across firms due to differences in the price of low and high sulfur fuels and the intensity of regulation. The potential savings from a cost minimizing reallocation of abatement resources are estimated for five regions. Current expenditures are found to be 47% higher than cost minimizing levels. I MPLEMENTATION of the 1970 Clean Air Act Amendments relies extensively on technology-based emission standards. Economists long have recognized that these standards can result in an inefficient allocation of pollution control resources.' Engineering-based restrictions ignore or oversimplify differences in abatement costs among polluters. Limited empirical research suggests that current standards result in substantially higher costs, as much as ten times higher, than a cost-minimizing regulatory scheme.2 These studies, however, are based on engineering estimates of marginal abatement costs. The models often assume that all polluters adopt control technologies that are required only for new plants and that have been largely unadopted by polluting firms.3 The impact of changing factor prices on marginal abatement costs typically is ignored. The difficulty is that the resulting estimates of the cost of regulation neither adequately reflect the range of control options available to polluters nor take into account how polluters actually have responded to environmen-

Recent theoretical models of entry predict that, in the presence of sunk costs, current market participation is affected by prior experience. This paper quantifies the effect of prior exporting experience on the decisions of Colombian manufacturing plants to participate in foreign markets. It develops a dynamic discrete-choice model of exporting behavior that separates the roles of profit heterogeneity and sunk entry costs in explaining plants' exporting status. Sunk costs are found to be significant, and prior export experience is shown to increase the probability of exporting by as much as 60 percentage points.

This paper measures and analyzes the effect of sulfur dioxide emission restrictions on the rate of productivity growth in the electric power industry over the 1973-79 business cycle. A firm-specific measure of regulatory intensity is developed which depends on the severity of the emission standard, the extent of enforcement, and the unconstrained emission rate relevant to each utility. The results indicate that emission regulations result in significantly higher generating costs, primarily from the increased use of low-sulfur fuels. The average rate of productivity growth was reduced by 0.59 percentage points per year for constrained utilities.

This paper measures and analyzes the effect of sulfur dioxide emission restrictions on the rate of productivity growth in the electric power industry over the 1973-79 business cycle. A firm-specific measure of regulatory intensity is developed which depends on the severity of the emission standard, the extent of enforcement, and the unconstrained emission rate relevant to each utility. The results indicate that emission regulations result in significantly higher generating costs, primarily from the increased use of low-sulfur fuels. The average rate of productivity growth was reduced by 0.59 percentage points per year for constrained utilities.

As the exchange rate, foreign demand, production costs and export promotion policies evolve, manufacturing firms are continually faced with two issues: Whether to be an exporter, and if so, how much to export. We develop a dynamic structural model of export supply that characterizes these two decisions and estimate the model using plant-level panel data on Colombian chemical producers. The model embodies uncertainty, plant-level heterogeneity in export profits, and sunk entry costs for plants breaking into foreign markets. Our estimates, and the simulation exercises that they support, yield several implications. First, entry costs are typically large, but vary greatly across producers. Second, there is substantial cross-plant heterogeneity in gross expected export profit streams. Third, these large entry costs make expectations about future exporting conditions important for many producers, so changes in the exchange rate regime that are credible induce much more entry than those that are not. Fourth, however, most of the entry and exit takes place among marginal exporters who contribute little to aggregate export revenues. Finally, subsidies on export earnings have a much larger impact on export revenues (per dollar spent) than subsidies that reduce the entry costs faced by new

This article quantifies the role of plant construction, expansion, contraction, and closing in generating net and gross changes in U.S. manufacturing employment over the 1963-82 period. A new longitudinal data set, constructed from the plant-level observations collected in the last five Census of Manufactures, is utilized. The reallocation of employment opportunities across and within sectoral, regional, and cohort boundaries is measured. Over 70% of the turnover in employment opportunities occurs across plants within the same two-digit industry and geographic region. Systematic differences in the employment fluctuations of plants of different ages are also found.

This note estimates the long-run demand for skilled and unskilled labor using panel data for Colombian manufacturing plants. Unobserved heterogeneity and measurement error problems that commonly arise in microdata production estimates are examined. Output measurement errors cause OLS estimators to underestimate the output and wage response of employment demand. Time-difference estimators exaggerate the measurement error biases. Instrumental-variable estimates of the output elasticities are 0.89 and 0.76 and own-wage elasticities are −0.42 and −0.65 for skilled and unskilled labor, respectively. The output elasticity is larger for skilled labor whereas the wage elasticity is larger for unskilled labor in virtually every industry.

This paper estimates a dynamic structural model of a producer's decision to invest in R&D and export, allowing both choices to endogenously affect the future path of productivity. Using plant-level data for the Taiwanese electronics industry, both activities are found to have a positive effect on the plant's future productivity. This in turn drives more plants to self-select into both activities, contributing to further productivity gains. Simulations of an expansion of the export market are shown to increase both exporting and R&D investment and generate a gradual within-plant productivity improvement.