Official Title



(School of Social Sciences)

Contact Information


Web Page URL

Grant-in-aids for Scientific Researcher Number



Faculty of Social Sciences(Graduate School of Social Sciences)

Affiliated Institutes


研究所員 2018-

Educational background・Degree

Educational background

-2007 New York University Economics


Ph.D. in Economics

Research Field


Macroeconomics, Economic growth, Technological change, Firm dynamics, Social learning

Grants-in-Aid for Scientific Research classification

Social sciences / Economics / Economic theory


Tolerance and Herd Behavior: Sophistication of Ideas under Payoff Complementarity

Koki Oikawa

Journal of Public Economic Theory 2011-

Uncertainty-driven Growth

Koki Oikawa

Journal of Economic Dynamics and Control 2010-

Acceleration Effect of Uncertainty on Technological Diffusion

Koki Oikawa

Economics Letters 2008-

Final Goods Substitutability and Economic Growth

Koki Oikawa

Economics Bulletin 2007-

Cyclical behavior of firm-level volatility: An explanation for the contrast between the United States and Japan

Oikawa, Koki

Journal of Macroeconomics 38(PB) p.452 - 4642013/12-2013/12




Outline:This study examines the cyclical behaviors of firm-level volatility, measured by real sales growth. Japanese firm-level data show that their volatility is countercyclical, whereas it is procyclical among the United States firms reported in a previous study. We formulate a theoretical model that accounts for these opposing behaviors over the business cycles. The key driving factor behind the relationship is the bankruptcy cost structure, more specifically, the relative magnitude of the fixed and marginal costs of bankruptcy. The fixed bankruptcy cost operates as an entry barrier and the marginal bankruptcy cost operates as an additional cost of hiring. These distinct impacts affect the type of firms entering/exiting the market over the business cycle. We also examine the welfare and policy implications of the model by comparing the structures of bankruptcy costs in terms of efficiency. © 2013 Elsevier Inc.

R&D in clean technology: A project choice model with learning

Oikawa, Koki; Managi, Shunsuke

Journal of Economic Behavior and Organization 117p.175 - 1952015/09-2015/09




Outline:© 2015 Elsevier B.V. In this study, we investigate the qualitative and quantitative effects of an R&D subsidy for a clean technology and a Pigouvian tax on a dirty technology on environmental R&D when it is uncertain how long the research takes to complete. The model is formulated as an optimal stopping problem, in which the number of successes required to complete the R&D project is finite and learning about the probability of success is incorporated. We show that the optimal R&D subsidy with the consideration of learning is higher than that without it. We also find that an R&D subsidy performs better than a Pigouvian tax unless suppliers have sufficient incentives to continue cost-reduction efforts after the new technology successfully replaces the old one. Moreover, by using a two-project model, we show that a uniform subsidy is better than a selective subsidy.

A microfoundation for stochastic frontier analysis

Oikawa, Koki

Economics Letters 139p.15 - 172016/02-2016/02




Outline:© 2015 Elsevier B.V. This paper provides a microfoundation for distributions of technical inefficiency in parametric stochastic production frontier analysis. It shows that dial-setting technology à la Jovanovic and Nyarko (1996) implies a gamma distribution with a specific set of parameters that depends on a manager's experience or his/her prediction ability.

The optimal inflation rate under Schumpeterian growth

Oikawa, Koki; Ueda, Kozo

Journal of Monetary Economics Peer Review Yes 100p.114 - 1252018/12-



Outline:To analyze the relationship between inflation and economic growth, we construct an endogenous growth model with creative destruction, incorporating sticky prices due to menu costs. Price changes reduce the reward for innovation and thus lower the frequency of creative destruction. Central banks can maximize the growth rate by setting their inflation target at the negative of a fundamental growth rate. While the optimal inflation rate may be greater than the growth-maximizing inflation rate, our calibrated model shows that the optimal inflation rate is close to the growth-maximizing inflation rate and that a deviation from the optimal level has sizable impacts.

Inter-firm Technological Proximity and Knowledge Spillovers

Koki Oikawa

Public Policy Review Peer Review Yes Invitation Yes 13(3) p.305 - 3242017/11-



Outline:This paper has two objectives. One is to survey previous studies concerning indicators of technological proximity and distance to identify technological relationships between firms, particularly in terms of spillovers of technology and knowledge. The other objective is to reexamine the spillover effect in research and development by combining the traditional technological proximity with a measurement of within-field technological relationships, which is based on patent citation overlaps. I find that the average technological proximity is increasing over these three decades in the United States and within-field technological proximity shows sizable variations, and that the spillover effect is underestimated unless the changes in within-field proximities are taken into account.

Short- and long-run tradeoff of monetary easing

Koki Oikawa; Kozo Ueda

Journal of the Japanese and International Economies Peer Review Yes 52p.189 - 2002019/06-2019/06



Publish Classification:Research paper (scientific journal)

Outline:In this study, we illustrate a tradeoff between the short-run positive and long-run negative effects of monetary easing by using a dynamic stochastic general equilibrium model embedding endogenous growth with creative destruction and sticky prices due to menu costs. Although a monetary easing shock increases the level of consumption because of price stickiness, it lowers the frequency of creative destruction (i.e., product substitution) because inflation reduces the reward for innovation via menu cost payments. When calibrated to the U.S. economy, the model suggests that the adverse effect dominates in the long run.

Research Grants & Projects

Grant-in-aids for Scientific Research Adoption Situation

Research Classification:

Firm size distribution and economic growth


Allocation Class:¥3770000

Research Classification:

Firm-level volatility and business cycles


Allocation Class:¥1690000

Research Classification:

Firm-level Volatility and Economic Growth

Allocation Class:¥1690000

Research Classification:

Theoretical and Experimental Research on Money and Market System in the Pacific Island Countries


Allocation Class:¥43810000

On-campus Research System

Special Research Project



Research Results Outline: 本研究では、研究開発補助金等の政策によってインセンティブを追加された民間の研究開発主体の行動分析を行った。科学技術開発のプロジェクトは最終的な成果が 本研究では、研究開発補助金等の政策によってインセンティブを追加された民間の研究開発主体の行動分析を行った。科学技術開発のプロジェクトは最終的な成果が出るまでに時間がかかる場合が多く、また、研究開発の緒に就いた段階では、必ずしも先の見通しは明確でな... 本研究では、研究開発補助金等の政策によってインセンティブを追加された民間の研究開発主体の行動分析を行った。科学技術開発のプロジェクトは最終的な成果が出るまでに時間がかかる場合が多く、また、研究開発の緒に就いた段階では、必ずしも先の見通しは明確でない。この性質を分析に取り込むため、研究開発を進めながら、同時にプロジェクトの質の評価を行い、最適なプロジェクトを模索しながら開発を進める研究開発主体を想定した。 研究開発主体の意思決定をモデル化するにあたり、ベイズ推定による、プロジェクトの性質についてのビリーフ更新を伴う最適停止理論を用い、新規技術の完成というゴールが設定されているところに特徴を持たせた。複数の研究プロジェクトが存在するケースにも容易に拡張できるが、アームド・バンディッドの枠組から逸れるため、計算量の負荷が増大しがちであり、その点は今後の課題といえる(現状では、2種類のプロジェクトを選べる状況を分析している)。いずれにしてもこうした理論化によって、環境汚染技術の負の外部性だけでなく、研究開発主体自身が、現在進めているプロジェクトがどの程度有望であるかを合理的に精査し、より良いプロジェクトを選択していく学習プロセスを、明示的に分析の俎上に載せられるところに本研究の貢献がある。さらに、理論を定量分析に繋げる試みとして、電気自動車の開発過程のデータを用いてモデルのパラメータを設定し、シミュレーションを行った。 本研究で得られた結論は以下の通りである。政策サイドが前述の学習プロセスの影響を考慮に入れないと、研究開発補助金は過少になる。また、環境効率の低い旧技術へのピグー税は、効率性の点で研究開発補助金を下回る。これは特に、複数のプロジェクトが存在する場合に顕著となる。シミュレーションによる定量分析では、学習プロセスを考慮に入れた最適な補助金政策を取ると、当該研究開発に関わる社会的便益が10%程度上昇することが示された。



Research Results Outline:本研究は、内生的成長の理論に価格の硬直性の要素を取り入れることによって、金融緩和やインフレと経済成長の関係を分析した。価格の硬直性があると、インフレや本研究は、内生的成長の理論に価格の硬直性の要素を取り入れることによって、金融緩和やインフレと経済成長の関係を分析した。価格の硬直性があると、インフレやデフレがイノベーションの報酬である新規企業の価値を削減し、創造的破壊の頻度の低下をもたらすことを理...本研究は、内生的成長の理論に価格の硬直性の要素を取り入れることによって、金融緩和やインフレと経済成長の関係を分析した。価格の硬直性があると、インフレやデフレがイノベーションの報酬である新規企業の価値を削減し、創造的破壊の頻度の低下をもたらすことを理論的に示した。中央銀行は、長期的なインフレ率をファンダメンタルな実質成長率に等しいデフレに設定することで、経済成長率を最大化することができるが、経済厚生上最適なインフレ率は、主として研究開発の過剰投資のため、成長を最大化するインフレ率を上回る可能性がある。ただし、カリブレートされたモデルでは、最適インフレ率が成長を最大化するインフレ率に近い。


2017Collaborator:Hiroshi Takahashi

Research Results Outline:We investigate the relationship between location choices of firms in a techWe investigate the relationship between location choices of firms in a technology space and innovations at the firm and tech...We investigate the relationship between location choices of firms in a technology space and innovations at the firm and technological category levels. We estimate firm distribution in a technology space with patent citation overlaps and trace the locational changes of each firm. We find that a firm generates more quality-adjusted patents if it moves less in the technology space it belongs, the average distance to other firms is smaller, and technology is less accumulated around that location. At the technological category level, patent productivity tends to be high with low average moving distance but high standard deviation of it, low average distance between firms, and high entry rate. We then develop an agent-based model that generates dynamic behaviors of firms in a technology space. In the model, a firm sequentially chooses its location to maximize firm value conditional on the location profile of other firms minus the cost of moving. The firm value depends on knowledge spillover and market competition, where those factors are related to technological distances. With agent-based simulation, we analyze the impacts of regulation shifts such as patent protection policy and R&D subsidy.



Research Results Outline: マクロ的な経済成長を維持するには、持続的な技術進歩が不可欠である。本研究は、仮想的な技術空間における企業の戦略的立地と、イノベーション成果の関係に基 マクロ的な経済成長を維持するには、持続的な技術進歩が不可欠である。本研究は、仮想的な技術空間における企業の戦略的立地と、イノベーション成果の関係に基づいて、ミクロ・マクロ両面から見て望ましイノベーション政策のあり方を探る試みである。 研究の第一段... マクロ的な経済成長を維持するには、持続的な技術進歩が不可欠である。本研究は、仮想的な技術空間における企業の戦略的立地と、イノベーション成果の関係に基づいて、ミクロ・マクロ両面から見て望ましイノベーション政策のあり方を探る試みである。 研究の第一段階では、企業が取得した特許データから抽出した企業間の技術的な距離を用いて、実際の技術空間上の企業立地の変化を追跡した。データから推計された移動距離や、移動先における企業集積状況など、立地が変化した時の特徴と、その後の各企業の特許申請状況を観察した。 研究の第二段階では、企業の技術立地モデルを作ってシミュレーションを行った。このモデルが有用であるのは、政策等の変化が引き起こす企業の技術的立地の内生的な変化を明示的に考慮した上で、影響を把握できる点にある。論文では、移動距離等の基本的な特性をモデルが再現できることを示した上で、特許保護を政策的に強めることで技術的距離が全体的に広がるように立地の変化が生じ、結果として特許保護のイノベーション促進効果を抑制することを示した。



Research Results Outline:Responding to increasing attention to the distributional aspects of monetarResponding to increasing attention to the distributional aspects of monetary policy, we investigate reallocation among heter...Responding to increasing attention to the distributional aspects of monetary policy, we investigate reallocation among heterogeneous firms triggered by nominal growth. Japanese firm-level data show that large firms tend to invest more in R&D and grow faster than small firms under higher inflation. We then construct a model that introduces nominal rigidity due to menu costs into R&D-driven endogenous growth with heterogeneous firms. The model shows that high nominal growth leads to an increase in the market share of innovative firms because menu-cost burdens are relatively heavier for less innovative firms. This reallocation effect leads to heavier tail of firm size distribution and yields a positive effect of monetary expansion on both real growth and welfare.

Lecture Course

Course TitleSchoolYearTerm
Advanced Macroeconomics A [E] 01School of Political Science and Economics2020winter quarter
Introduction to Economics 2 [Macroeconomics] ASchool of Social Sciences2020fall semester
SeminarI (Applied Macroeconomics/fall semester)School of Social Sciences2020fall semester
SeminarII (Applied Macroeconomics)School of Social Sciences2020fall semester
SeminarIII (Applied Macroeconomics)School of Social Sciences2020fall semester
Applied MacroeconomicsSchool of Social Sciences2020fall semester
Macroeconomics III(General Equilibrium)(Oikawa, K)Graduate School of Economics2020winter quarter
Advanced MacroeconomicsGraduate School of Social Sciences2020fall semester
MacroeconomicsGraduate School of Social Sciences2020winter quarter
Macroeconomics I (fall semester)Graduate School of Social Sciences2020fall semester
Macroeconomics II (fall semester)Graduate School of Social Sciences2020fall semester

Waseda Course Channel Video Service

Course TitleFacultyPublication Year