20120829program

20120829program

要旨：The U.S. regional data shows that there is observed a tendency that the skill premium in a region is positively correlated with the relative supply of skill in that region, which suggests there exists something beyond the law of supply and demand. Unlike the typical interpretation by urban economists, this paper provides a simple static two-region general equilibrium model of comparative advantage with monopolistic competition, interpreted as skill-biased technical change, in order to explain the fact without relying on technological externality. It is shown that the ex-ante identical regions specialize in industries with different skill intensities as a result of circular causation working through the interaction between comparative advantage and skill-biased technical change, and the associated essentially unique equilibrium exhibits the positive correlation under a certain set of parameters. The model is then extended by introducing a technological externality in order to argue that technological externality itself does not guarantee welfare improvements given the existence of scarce land. More importantly, it is also argued that the economy-wide skill-biased technical change by reducing the benefit from specialization acts as a dispersion force, and thus it could reduce the welfare gain from technological externality.

要旨：This paper examines the relation between regional unemployment disparities and agglomeration in the presence of labor market frictions. It combines a footloose entrepreneur model with Diamond-Mortensen-Pissarides matching and screening frictions in the labor market within the differentiated-product sector. Under spatial mobility of entrepreneurs, the local unemployment rate is higher in the region with firm agglomeration because of the impact of sectoral allocation among local workers. Regarding the unemployment rate within the local differentiated sector, however, regional market access matters. Given that the spatial equilibrium might be affected mainly via the forward linkage, agglomeration does not necessarily generate a higher unemployment rate within the differentiated sector. Regional unemployment disparities are magnified when regions are more integrated or when labor market friction increases.

要旨：This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution for a sequence of links is also a stable distribution. The parameters of the travel time distribution for a sequence of links can then be derived analytically from the link level distributions.