要旨：本研究では、事前・事後割引料金システムの経済厚生を比較する。事前割引料金システムでは、実際の交通サービスの利用に先立って、サービス対価の支払い額が確定している。一方、事後割引料金システムでは、事前に料金メニューのみが提示され、家計のサービス行動に応じて料金が事後的に決定される。このように、事前・事後割引料金システムでは家計と企業のリスク分担構造が異なる。本研究では、以上のリスク分担構造を考慮した３期間モデルを定式化し、事前・事後割引料金システムが企業の利潤、家計の厚生に及ぼす影響を理論的に分析する。その結果、既存の料金システムを併存しつつ、新しく割引料金システムを導入する場合、事後割引料金システムの方が社会的厚生の観点から望ましい結果をもたらすことが明らかになった。

要旨：In an international oligopoly model, this paper investigates interaction between trade liberalization in goods and liberalization in service FDI. Since some services are market-specific and have non-tradable nature, a foreign firm has a higher cost in service provisions compared to its domestic competitor and it can overcome the disadvantage by either outsourcing services to the domestic competitor or making service FDI. When the cost of service FDI is high enough, trade liberalization under service outsourcing may have an anti-competitive effect and benefit both domestic and foreign firms at the expense of consumers. A decline in the cost of service FDI makes this paradoxical effect less likely, and trade liberalization becomes pro-competitive when the cost is low enough so that the foreign firm actually makes service FDI.

要旨：While the most of the theoretical models of social networks are inherently dynamic, the majority of the existing empirical studies of the social networks are static. This paper is an attempt to enrich the field by providing an empirical analysis of evolving networks of successful R&D collaborations in the IT industry in the United States between 1985 and 1995. We first measure the properties of the network over time and demonstrate that the network has become more extensive, more clustered, and more unequal in the sense "star" companies have emerged in the network. We then estimate the strength of various mechanisms that have been proposed in the literature as driving forces behind the network evolution. After controlling for the similarity of firms as much as possible, including some unobserved similarities among firms by extracting the community structure defined within the network, we find there are significant "triadic closure bias" and "preferential attachment bias".

要旨：本論文では、地価への空間自己相関モデルの適用を例に、空間構造の近接行列による特定化について検討した。特に空間的に双方向的な相互依存関係ではなく、(時系列分析に類似した) 一方向的な影響を表現した方が適合性が高い場合があるを確認した。空間的依存関係はごく一般的に存在すると推測される一方、計量経済学的分析において空間自己相関モデルが採用されることは多くない。本論文の結果は、その原因の一つとして従来の研究での相互依存の仮定が強すぎたという可能性があることを示唆している。

要旨：How is long run economic growth related to the diversity of knowledge? We formulate and study a microeconomic model of knowledge creation, through the interactions among a group of R & D workers, embedded in a growth model to address this question. Income to these workers accrues as patent income, whereas transmission of newly created knowledge to all such workers occurs due to public transmission of patent information. Our model incorporates two key aspects of the cooperative process of knowledge creation: (i) heterogeneity of people in their state of knowledge is essential for successful cooperation in the joint creation of new ideas, while (ii) the very process of cooperative knowledge creation affects the heterogeneity of people through the accumulation of knowledge in common. The model features myopic R & D workers in a pure externality model of interaction. Surprisingly, in the general case for a large set of initial conditions we find that the equilibrium process of knowledge creation converges to the most productive state, where the population splits into smaller groups of optimal size; close interaction takes place within each group only. Equilibrium paths are found analytically. Long run economic growth is positively related to both the effectiveness of pairwise R & D worker interaction and to the effectiveness of public knowledge transmission. If we define efficiency constrained by the monopolistic competition environment for consumption goods, our equilibrium paths are constrained efficient.

【応用ミクロ経済学・産業経済学ワークショップと共催】

要旨：We propose a novel long-term migration dynamics that can overcome the equilibrium indeterminacy of Core-Periphery (CP) model a la Krugman [1991b]. This goal is achieved by introducing uncertainty of economic environment into CP model with forward-looking migration dynamics. We show that an equilibrium path of migration dynamics can be uniquely determined in accordance with each stochastic sample path.