Cities, Workers, and Wages: A Structural Analysis of the Urban Wage Premium

Workers earn higher wages in cities vs. rural areas. This gap could arise because cities make workers more productive, or it could be the result of a non-random selection of workers into cities based on their ability and their endogenous history of career choices. To untangle these issues, this paper estimates a dynamic programming model, which embeds the choice of residing in a city or rural area within a model of career choices over time. After controlling for all the sources of selection and endogeneity, the estimates indicate that a given worker does earn more in the city for white-collar work, but not for blue-collar work. In addition, city work experience is found to be worth more than rural work experience in the rural area for white-collar work, but not for blue-collar work. These results support the interpretation that cities make white-collar workers more productive and suggest that workers may consider moving to the city not only in terms of locational choice, but also as a form of human capital investment.     

Bioenergy Crop Production in the United States: Potential Quantities, Land Use Changes, and Economic Impacts on the Agricultural Sector

The U.S. Departments of Agriculture and Energyjointly analyzed the economic potential for,and impacts of, large-scale bioenergy cropproduction in the United States. Anagricultural sector model (POLYSYS) wasmodified to include three potential bioenergycrops (switchgrass, hybrid poplar, and willow). At farmgate prices of US $2.44/GJ, anestimated 17 million hectares of bioenergycrops, annually yielding 171 million dry Mg ofbiomass, could potentially be produced at aprofit greater than existing agricultural usesfor the land. The estimate assumes highproductivity management practices are permittedon Conservation Reserve Program lands. Traditional crops prices are estimated toincrease 9 to 14 percent above baseline pricesand farm income increases annually by US $6.0billion above baseline.At farmgate prices of US $1.83/GJ, anestimated 7.9 million hectares of bioenergycrops, annually yielding 55 million dry Mg ofbiomass, could potentially be produced at aprofit greater than existing agricultural usesfor the land. The estimate assumes managementpractices intended to achieve highenvironmental benefits on Conservation ReserveProgram lands. Traditional crops prices areestimated to increase 4 to 9 percent abovebaseline prices and farm income increasesannually by US $2.8 billion above baseline.     

A Markov–switching vector equilibrium correction model of the UK labour market

There is a wide literature on the dynamic adjustment of employment and its relationship with the business cycle. In this paper we present a statistical model that offers a congruent representation of part of the UK labour market since the mid 1960s. We use a cointegrated vector autoregressive Markov-switching model in which some parameters change according to the phase of the business cycle. Output, employment, labour supply and real earnings are found to have a common cyclical component. The long run dynamics are characterized by one cointegrating vector relating unemployment to trend-adjusted real wages and output. Despite there having been many changes affecting this sector of the UK economy, the Markov-switching vector-equilibrium-correction model with three regimes (representing recession, normal growth, and high growth) provides a good characterization of the sample data, and performs well relative to alternative linear and non-linear models. The results of an impulse-response analysis highlight the dangers of using VARs when the constancy of the estimated coefficients has not been established, and demonstrate the advantages of generating regime dependent responses. First Version Received: December 2000/Final Version Received: August 2001     

实际汇率、工资和就业--对中国贸易部门和非贸易部门的实证研究

在同时考虑贸易部门和非贸易部门的情况下,实际汇率贬值会增加贸易部门就业,但会减少非贸易部门就业,对实际工资的影响则是不确定的.按照理论分析的结果,文章对人民币实际汇率和中国两部门实际工资及就业的关系进行协整检验,结果发现:人民币实际汇率贬值显著增加贸易部门就业,但非贸易部门就业对实际汇率变动不敏感,而两部门的实际工资和实际汇率之间则都没有协整关系存在.进一步检验发现实际汇率变动对就业在贸易和非贸易部门之间的结构也没有影响.总的结论认为,即使考虑到非贸易部门,人民币实际汇率升值对整个就业也是不利的,而贬值有利于整个就业.     

The demographic impact of AIDS in sub-Saharan Africa: short- and long-term projections

"This paper describes the methodology used to incorporate AIDS mortality in recently revised World Bank population projections....The paper first reviews different approaches for projecting AIDS and its demographic consequences. This is followed by a summary of an epidemiological model that simulates the spread of HIV used in this analysis, and a demographic model that translates mortality from AIDS into population outcomes. These models are then used in a set of simulations, from which the effect of current HIV prevalence on projected future mortality is extracted. Finally, the extracted equations linking current HIV prevalence with future mortality indicators are applied to sub-Saharan countries with a measurable level of current HIV prevalence."     

Common factors can always be found but can they also be rejected?

Factor models are often used to reduce the complexity of data. It is simple to find common factors and to interpret them. However, it is doubtful whether factor models are always appropriate. Especially when the common factor is considered to be an attitude, it must be stable through time and explain a considerable part of the variances. A procedure is suggested to test the usefulness of a common factor. In an experimental pilot study in which an attitude towards immigrant workers was investigated, the instability and superfluousness of a common factor is shown. An alternative model is presented which suggests that changing opinions can be explained by specific variables. Finally it is shown that a more stable common factor is found if a so-called MIMIC-design is used.