要旨：COVID-19が猛威を振るう昨今、感染拡大に寄与した要因を明らかにすることは喫緊の課題となっている。陽性者数や死者数の分析には、ポアソン回帰やその拡張手法が用いられてきた。しかしながら、ポアソン回帰には次の課題が残されている：(i)ゼロ値の多いカウントデータの場合は解が識別できず、この問題はモデルが複雑化するほど深刻化する；(ii)そもそも陽性者数や死者数がポアソン分布に従うとは限らない。そこで本研究では、課題(i)、(ii)に対処することで、多種多様な要因の影響を安定的に推定するための新たな回帰手法を開発する。同開発では、課題(i)に対処するための新たな対数線形近似を提案し、次に課題(ii)に対処するためのデータ分布の自動推定手法を提案する。最後に、開発した手法をCOVID-19の地理的要因の分析に応用することで、人流、世代、政策などの各種要因の感染拡大に対する影響を評価する。

要旨：所有権移転登記は、不動産の変化を捕捉する際、包括的かつ正確な情報を有している。本報告では不動産の流動に着目し、移転登記目的別の流動量の空間的傾向や人口増減などの要因との相関関係を考察する。全体的な傾向として、移転登記件数は都市圏規模に比例する一方で、大規模災害などの事象によりその流動性を増加させる自治体も存在した。さらに、移転登記と地域環境変数との対応から、登記目的によって両者の相関の程度が異なることが明らかになった。上記の知見に加えて、本報告では国勢調査小地域単位あるいは3次メッシュ単位での追加分析も加え、考察を深める。このような不動産流動の理解は、土地・建物の管理の限界や、国庫へ帰属すべき土地の検討などにも関連すると考えられ、更なる分析を通して政策的含意へとつながる研究へ発展させる予定である。

《参考資料》

馬塲弘樹, 眞木仁, 高野佳佑, 清水千弘. 2021. 所有権移転登記情報からみた不動産市場の流動性—不動産流動統計を用いた分析—. CSIS Discussion Paper, 173.

配布資料：論文, 付録

要旨：This paper revisits the core-periphery model of Krugman (1991) when his CES utility is replaced by a general additively separable sub-utility which captures the income effect and allows variable markups. New evolving paths and bifurcation patterns are created by the interaction between the agglomeration force generated by monopolistic competition, increasing returns to scale, trade cost and the dispersion force resulting from the pro-competitive effect. Autarky does not necessarily produce full dispersion and free trade may not correspond to agglomeration. Moreover, the demand parameter of manufactured goods is crucial to determining the firm location.

要旨：This talk will firstly review observed trends among public transport operators regarding fare polices and discuss that both simplification and “optimisation by differentiation” trends exist. If revenue and demand management optimal fares are desired, also in urban settings distance and route depending fares are increasingly an option due to new data collection technologies. This leads to modelling challenges such “hyperpaths with non-additive costs” which will be discussed in the second part. In the third part then the impact of new transport forms, in particular shared transport and “cheap taxis” is discussed. The competition and collaboration potential will be highlighted. The talk will close with some thoughts on how electrification of the transport system and vehicle to grid services might also impact fares and revenues.

要旨：In their model of monopolistic competition with firm heterogeneity and variable markups, Nocco, Ottaviano, and Salto (2014) show firm heterogeneity and markup pricing create distortions at market equilibrium, which can be removed by a first-best policy if a firm-specific per-unit tax/subsidy is available. This study provides an alternative first-best policy without adopting a firm-specific tax/subsidy. The first-best outcome can be decentralized through a uniform ad valorem production tax and a uniform per-unit production subsidy, accompanied by a lump-sum tax on consumers. This indicates that policymakers can design the first-best policy without observing firm private information in terms of productivity.

要旨：Most metropolitan areas in the U.S. have been developed around the automobile, making driving essential to accessing opportunities.  Despite high rates of driving, some adults do not drive.  A majority of non-drivers face significant barriers to driving, one of which is state driver’s license regulations that deny driving privileges to unauthorized immigrants. However, 15 states and the District of Columbia have adopted laws allowing unauthorized immigrants to acquire driver licenses and, therefore, to legally drive.  In this study, we draw on annual data from the American Community Survey from 2006 to 2018 to examine the relationship between the adoption of state driver’s licensing laws for unauthorized immigrants and changes in automobile commuting and commuting by public transit.  We focus on unauthorized Latinx immigrants in California, the state with the largest percentage of unauthorized residents.  We then test to see whether the effects are similar in other states that have recently adopted comparable driver’s licensing regulations. Many unauthorized immigrants in California have obtained driver’s licenses through Assembly Bill 60 (AB 60) allowing them to drive legally. Our analysis shows that AB 60 had a small positive effect on auto commuting and a small negative effect on transit commuting among unauthorized Latinx immigrants in California but, likely, little or no effect in states outside of California. Combined with its role in reducing hit and run accidents and potentially easing immigrants’ fears of police stops, the evidence suggests that AB 60 has contributed to the enhanced mobility and safety of unauthorized immigrants and their families.

要旨：神戸市全体の大規模交通シミュレーションを実行した結果、交通量に対して道の本数をプロットすると、冪的な関係に従うことが明らかとなった。その起源について数学的なモデルを立て、冪的な分布が生じた理由について考察する。また、阪神高速のETCデータを分析したところ、ODには強固な規則性が存在することが示唆されたが、2020年にはCOVID19の影響により規則性が破れている様子が観察されたため、これについても報告する。

《参考資料》

Umemoto and Ito, Journal of Computational Social Science, 2018

Umemoto and Ito, Journal of Computational Social Science, 2019

要旨：We construct a model in which there are oligopolistic firms that can influence the aggregate market conditions and monopolistic firms which cannot influence the aggregate market. We assume that both types of firms can conduct R&D investments to improve their productivities. When the R&D cost of oligopolistic firms is sufficiently lower than monopolistic firms, oligopolistic firms can survive as big firms, which can manipulate the market, dominate the market and conduct the larger R&D investments. We show that with the increase in the market size, the relative outputs and R&D investments of oligopolistic firms compared to monopolistic firms are raised, and consequently, the survival of big firms becomes easy. We show that there is a subsidy policy that enables the economy to achieve the second-best allocation.