Ishibashi, Koji

写真a

Affiliation

Faculty of Economics （Mita）

Position

Professor
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Message from the Faculty Member 【 Display / hide 】

  • 経済問題や経済現象を論理的に考察し、分析する能力が経済学部の学生に期待されていることだと思います。特にミクロ経済学・マクロ経済学・数学・統計学の知識や能力は三田の専門課程での学習のみならず、社会に出てからも非常に有用になります。のちに後悔することのないように、日吉のときから地道に学習されることを望んでいます。

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Career 【 Display / hide 】

  • 1990.04
    -
    1997.03

    大学助手(経済学部)

  • 1997.04
    -
    2010.03

    大学助教授(経済学部)

  • 1997.10
    -
    1999.09

    大学経済学部学習指導副主任

  • 2001.07
    -
    2001.09

    大学経済学部運営委員

  • 2001.07
    -
    2001.09

    大学経済学部学習指導主任

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Academic Background 【 Display / hide 】

  • 1998.01

    Boston University, －

    United States, Graduate School, Completed, Doctoral course

  • 1992.03

    Keio University, Graduate School, Division of Economics

    Graduate School, Withdrawal after completion of doctoral course requirements, Doctoral course

  • 1989.03

    Keio University, Graduate School, Division of Economics

    Graduate School, Completed, Master's course

  • 1987.03

    Keio University, Faculty of Economics

    University, Graduated

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Academic Degrees 【 Display / hide 】

  • Ph.D., Boston University, 1998.01

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Research Areas 【 Display / hide 】

  • Humanities & Social Sciences / Economic theory (General Theory of Economics)

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Research Themes 【 Display / hide 】

  • 混合寡占市場における品質競争と公企業の部分的民営化に関する理論的研究, 

    2002
    -
    2004

    　View Summary

    民間企業と公企業とが共存する寡占市場における価格・品質競争を想定して、公企業を部分的に民営化することの経済的根拠を分析している。

  • 企業内の非対称情報と市場競争との関係についての理論的研究, 

    1998
    -
    2004

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Books 【 Display / hide 】

  • Industrial Organization: A Synthesis of Theory and Empirics

    石橋　孝次, 慶応義塾大学出版会, 2021.09,  Page： 545

  • クルーグマン　マクロ経済学

    ISHIBASHI KOJI, 東洋経済新報社, 2009.04

  • クルーグマン　ミクロ経済学

    ISHIBASHI KOJI, 東洋経済新報社, 2007.10

  • 現代ミクロ経済学：中級コース

    ISHIBASHI KOJI, 有斐閣, 2006.02

  • インセンティブ契約と市場競争

    石橋　孝次, 三菱経済研究所, 2002.05

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Papers 【 Display / hide 】

  • Effects of Asymmetric Information within a Firm on Oligopolistic Market Outcomes

    ISHIBASHI KOJI

    Japanese Economic Review 61 （ 4 ） 488-506 2010.12

    Research paper (scientific journal), Single Work, Accepted

    　View Summary

    I analyze the implications of the Laffont-Tirole type agency problems on oligopolistic market outcomes. In the model, a firm's marginal cost is decreasing in managerial effort and is subject to an additive shock. Both managerial effort and the realization of the shock are a manager's private information. A firm first offers a menu of contract to its manager, and then competes in the product market. As in the model of single principal and single agent, the incentive contracts implement efforts that are distorted downward relative to full information. In this model, with multiple agency relationships, an additional source for upward distortion of effort emerges as a result of the interaction in the product market. The results are robust to whether firms compete in price or quantity.

  • Partial Privatization in Mixed Duopoly with Price and Quality Competition

    ISHIBASHI KOJI

    Journal of Economics 95 （ 3 ） 213-231 2008.12

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    We analyze price and quality competition in a mixed duopoly in which a profit-maximizing private firm competes against a state-owned public firm. We first show that the welfare-maximizing public firm provides a lower quality product than the private firm when they are equally efficient. In order to maximize social welfare, government manipulates the objective of the public firm that is given by a convex combination of profits and social welfare. It is demonstrated that an optimal incentive of the public firm is welfare maximization under the absence of quality competition, but it is neither welfare maximization nor profit maximization under the presence of quality competition. The result supports a completely mixed objective between welfare and profit maximizations or partial privatization of the public firm.

  • Strategic Delegation under Quality Competition

    Koji Ishibashi

    Journal of Economics Vol.73 （ 1 ） 25-56 2001.03

    Research paper (scientific journal), Single Work, Accepted

    　View Summary

    This paper examines strategic manipulations of incentive contracts in a model where firms compete in quality as well as in price. Compensation schemes for managers are based on a linear combination of profits and sales. For a given level of quality, a firm desires to reduce the manager's compensation when product sales increase; this serves as the firm's commitment to raise prices. Nevertheless, in general, a manager has a stronger incentive to produce goods of higher quality if he is compensated according to sales. Therefore, a compensation scheme that penalizes a manager when sales increase may result in products that are inferior to those of its rival. We show that, depending on the nature of quality, a positive weight on sales may be desirable when firms compete in quality and price. Welfare implications are also explored.

  • Labor Efforts, Interpersonal Comparisons of Utility and Optimal Taxation

    かわまたくにお、いしばしこうじ

    Keio Economic Studies Vol.34 （ 1 ） 1-19 1997

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    We study the structure of optimal taxation in an economy composed of individuals with the same characteristics except for their productive abilities. We compare the optimal outputs, consumptions and tax rates corresponding to Harsanyi, Nash and Rawls solutions. Some definite results are obtained when there are two types of consumers, and specific studies are made on proportional taxation. We will also give conditions under which the utility level of the more able individual is lower than that of the less able individual and argue that the more able individuals have incentive to pretend to be less able if separate tax rates are applied.

  • The Role of Tariffs in Entry Promotion and Deterrence under International Oligopoly

    Koji Ishibashi

    Keio Economic Studies Vol.28 （ 2 ） 13-29 1991

    Research paper (scientific journal), Single Work, Accepted

    　View Summary

    'The author considers a situation where a domestic firm tries to enter the home and foreign markets which are monopolized by a foreign incumbent. The international entry game consists of the home and foreign governments' choices of import tariffs and the entry decision of the domestic firm with technological disadvantage. It is shown that the optimal use of import tariffs may lead to entry promotion or deterrence, depending on the parameters of the demands and costs functions. The author also consider the welfare implications of the Nash tariff equilibrium.'

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Courses Taught 【 Display / hide 】

  • TOPICS IN APPLIED ECONOMICS AND POLICY

    2024

  • SEMINAR: MICROECONOMICS

    2024

  • SEMINAR: INDUSTRIAL ORGANIZATION

    2024

  • SEMINAR: APPLIED ECONOMICS AND POLICY

    2024

  • RESEARCH SEMINAR D

    2024

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