Updated on 2026/03/07

写真a

 
EBINA TAKESHI
 
Organization
Undergraduate School School of Commerce Professor
Title
Professor
External link

Degree

  • 博士（工学） ( 2010.3   東京工業大学 )

Research Areas

  • Humanities & social sciences / Economic policy

Research History

  • Meiji University   School of Commerce   Professor

    2022.10

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  • Meiji University   School of Commerce   Associate Professor

    2017.9 - 2022.9

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  • Shinshu University   Associate Professor

    2016.4 - 2017.9

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  • Shinshu University   Associate Professor

    2015.7 - 2016.3

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  • Shinshu University   Lecturer

    2013.4 - 2015.6

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  • Tokyo University of Science   Assistant Professor

    2010.3

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Professional Memberships

Papers

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MISC

Awards

  • 2012年度 日本応用経済学会奨励賞（単独受賞）

    2012.11   日本応用経済学会  

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Research Projects

  • 不確実性下の企業の投資行動と最適政策

    Grant number：21K01468  2021.4 - 2025.3

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    海老名 剛

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    Grant amount：\3640000 （ Direct Cost: \2800000 、 Indirect Cost：\840000 ）

    研究実施計画において，2021年度の目標は，1.現実に近い確率過程を導入した連続時間動学モデルを構築し，企業が，製品差別化（ポジショニング，立地），および投資時点に関する意思決定を行うモデルを構築することであった．そのうえで，2.状態遷移確率のような，一定の確率で不確実性が高い状態と低い状態をスイッチするようなモデルを構築することを，目標としていた．
    そこで，1.と関連して，ホテリングによる立地－価格競争モデルに，市場規模が幾何ブラウン運動に従い不確実性を伴う設定を導入し，製品差別化，および参入時点に関する分析を行った．結果として，規模に関するボラティリティ（不確実性）が高まると，リーダーはより差別化した製品を投入することを示した．また，フォロワーの参入時点が，ボラティリティに関して，非単調となることを示した．特に，後者の結果は，リアルオプション理論が通常示唆する結果と大きく異なる点である．本研究成果をまとめた論文が，国際学術雑誌European Journal of Operational Researchに採択された．
    2.と関連して，消費者の選好がブラウン運動に従い，かつ，トレンドやボラティリティが複数の状態で遷移するという2種類の不確実性があるモデル（レジーム・スイッチングモデル）を構築した．そして，状態遷移がない状況とある状況とで，企業の再差別化（リポジショニング，再立地）およびその閾値がどのように変化するかについて，考察した．結果として，状態遷移確率が上昇すると，閾値が非単調に変化することがわかった．既に，本研究成果を論文としてまとめ，英文校正によるチェックを受けたため，2022年度に，国際学術雑誌へ投稿予定である．

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  • M&As and innovation strategies and Competition Policy

    Grant number：18K01627  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Ebina Takeshi

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    Authorship：Principal investigator 

    Grant amount：\3510000 （ Direct Cost: \2700000 、 Indirect Cost：\810000 ）

    This research constructed a dynamic model that incorporates parameters related to the future economic environment (growth rate, discount rate, uncertainty, synergy effect, etc.), and clarified corporate innovation strategies (new-product development), M&A strategies (form of amalgamation, timing of M&As), and optimal policies.
    I showed the following four points: First, when launching a new product, it is important to focus on peaks and ends of consumer utility. Second, even if the synergy effect is negative, the firm has an incentive to take over. Third, even if there is no synergy effect, sequential mergers may improve social welfare. Finally, although full and partial privatization is desirable, full privatization is not desirable from the viewpoint of social welfare.

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  • Merger Strategy and Its Application to Competition Policy

    Grant number：15K17047  2015.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    Ebina Takeshi

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    Authorship：Principal investigator 

    Grant amount：\3770000 （ Direct Cost: \2900000 、 Indirect Cost：\870000 ）

    I examine optimal merger strategies and merger policies with differentiated goods under a dynamic setting. First, after one merger, other firms are willing to follow with their own merger, resulting in sequential mergers. Our analysis can be applied to many industries, such as bank, steel, and pharmaceutical. Second, given some preexisting mergers, further mergers may actually improve welfare. However, these welfare improving mergers may not be privately profitable, implying that merger-friendly policies are appropriate. Thus, in contrast to results of related literature, it may be better for the policymaker to encourage these welfare-improving mergers to be completed.

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  • Economic Analysis on competition policy and vertically related markets

    Grant number：15H03349  2015.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    MATSUSHIMA Noriaki, ISHIBASHI Ikuo, MIZUNO Keizo, SHIMIZU Daisuke, ZHAO Laixun, CHEN Zhijun, CHOE Chongwoo, KING Stephen, MACHO-STADLER Inés, PAN Cong, SATO Misato, YOSHIDA Shohei

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    Authorship：Coinvestigator(s) 

    Grant amount：\8580000 （ Direct Cost: \6600000 、 Indirect Cost：\1980000 ）

    Theoretical economic analysis is indispensable to understand the impact of economic activities under vertically related markets on economic welfare. We mainly analyzed many market environments with vertical relations, which contributes to the discussion on competition policy. Throughout the project, the bargaining powers of agents in each market environment substantially influence the predicted outcomes. For instance, under a bilateral monopoly market with a manufacturer and a retailer, the manufacturer opens its direct distribution channel to improve its disagreement payoff if its bargaining power over the retailer is not sufficiently strong. The effect of the opening on economic welfare depends on the efficiency of the direct distribution channel. When the retailer and the direct distribution channel compete in quantity, the opening harms economic welfare if the efficiency of the direct distribution channel is slightly worse than that of the retailer.

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  • The effect of product differentiation selection on merger criteria

    Grant number：24530264  2012.4 - 2016.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    Shimizu Daisuke, EBINA Takeshi

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    Authorship：Coinvestigator(s) 

    Grant amount：\4810000 （ Direct Cost: \3700000 、 Indirect Cost：\1110000 ）

    We proceeded with theoretical analysis of mergers, product differentiation with locations, and product differentiation with differentiated demand function in order to make policy implications regarding mergers in differentiated markets.
    In our 11 papers, we derived results that are counter to conventional wisdom in areas such as parameter conditions that bridge theoretical and empirical analyses, other disciplines such as engineering and marketing, and competition policy regarding mergers. In particular, we explain the last point. Mergers between similar firms tend to decrease social welfare, so the antitrust authorities are expected to block such mergers. However, we show that there are cases in which social welfare increases when sequential mergers occur after some mergers have already occurred. In such cases, it is better for the social planner to support these later mergers.

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  • A Research on Location Choice of Firms and Its Applications to Competition Policy

    Grant number：24730224  2012.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    TAKESHI EBINA

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    Authorship：Principal investigator 

    Grant amount：\3380000 （ Direct Cost: \2600000 、 Indirect Cost：\780000 ）

    The purpose of this study is to investigate a location choice of firms and to offer a policy implication. First, I construct a unidirectional model where consumers can only buy from one direction. I show that the equilibrium outcome of the previous study does not constitute a subgame perfect Nash equilibrium. In addition, applying my conjoint analysis to the book market of Japan, I investigate the relationship between product attributes and the optimal price. Second, I study the price and welfare effects of a merger of firms producing unidirectional complements. I show that a merger raises a price of a good, resulting in lower consumer surplus. This result is in sharp contrast to Cournot's classical implication that a merger in strict complements makes all consumers strictly better off. Furthermore, I apply a method, which utilizes the idea of pass-through in an analysis of third-degree price discrimination, to compare consumer surplus under vertical integration and separation.

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  • 経済組織における参照点（reference point）の影響と形成：行動経済学の理論的研究

    2011.4 - 2012.3

    財団法人全国銀行学術研究振興財団  学術研究助成金  競争的資金

    加藤 晋, 海老名 剛

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    Authorship：Coinvestigator(s) 

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  • 非対称的な混合組み合わせ販売における価格付けの理論的・実証的研究

    2009.4 - 2010.3

    財団法人日本経済研究奨励財団  日本経済研究財団奨励金  競争的資金

    安達 貴教, 海老名 剛, 花薗 誠

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    Authorship：Coinvestigator(s) 

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