要旨：This paper examines a conventional assumption of transport costs; any bilateral transport costs are symmetric. Using a comprehensive dataset on transport transactions in Japan, we first describe a directional imbalance of transport costs by transport mode and examine its potential sources such as density economies, long-haul economies, and a directional imbalance of transport flow. Based on the method of instrumental variables, we find that the density economies drive a deviation from symmetric transport costs between prefectures. We then develop a theoretical model of economic geography in which asymmetric transport costs occur in a transport sector for the density economies. Compared with the model without density economies, we show that agglomeration of economic activities is likely to emerge under any ranges of cost parameters. Thus, the economies of density in transport flows act as an agglomeration force.

要旨：In a closed monocentric city with three distinct land use patterns consisting of firms, condominiums and housing lots, we determine simultaneous optimization of regulations on building size, lot size and zonal boundaries under the existence of agglomeration externality in the business district and of traffic congestion externality in the residential zones. Results show that the optimal regulations are at most second best, and require not only downward adjustment to the market size of buildings at outer locations using maximum FAR regulation but also upward adjustment at more central locations using minimum FAR regulation within the business district, and similar regulations in the condominium zone, followed by a cap on the minimum lot size in the suburb. Moreover, the optimal city size is more compact than a market city, but whether the business district size should be compact or greater, depends on the relative level of agglomeration externality and the congestion. In addition, the boundary between condominium zone and housing lot zone does not need to be controlled.

要旨：我が国のタクシー産業は1993年から段階的に規制緩和が実施されており特に2002年の規制緩和は需給調整機能の廃止を目的とした参入規制や運賃制度の緩和が実施された。本研究の目的は我が国のタクシー産業における需要関数の推計を行い、2002年の規制緩和が消費者の動向へ与えた効果を計測することである。推定結果によれば需要の価格弾力性は負であり、運賃と2002年規制緩和ダミーの交差項は正に有意であるので、価格弾力性は0へ近づいた。つまり、規制緩和によって需要の価格弾力性が小さくなり、消費者にとってタクシーが必需品に近づいたと言える。これは規制緩和に伴って発生した各種新サービスが有効に機能した結果と考えられる。

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.

要旨：This paper empirically examines whether the geographical proximity of transaction partners improves the firms' profits by using the actual microdata on inter-firm transactions. I model the formation of transaction partners between newly entering firms and existing firms as a two-sided many-to-many matching game with transferable utility and estimate the structural parameters of the model. In the results, I find that the average distance to the transaction partners negatively affects the firms' structural revenues. This strongly suggests that the existence of agglomeration economies results from the inter-firm transactions that occur between geographically close firms. Furthermore, this effect is larger for entrant firms than existing firms.