Upcoming Seminars

場所：2号館11階経済学部会議室B

Venue: 11th Floor, Bldg. No.2 Meeting Room B 

幹事/Organizer：釜賀浩平/Kohei Kamaga

言語/Language：日本語/Japanese

要旨/Abstract: マッチング理論には、十分に研究が進んでいない問題がいくつか存在する。その一つは、エージェントをある組織に割り当てる際、各組織に最低限割り当てるべきエージェントの人数と、特定のタイプのエージェントに限定した最低限割り当てるべき人数の制約が同時に設けられている問題である。もう一つの問題は、エージェントが階層的なタイプを持つ場合において、公平な帰結が得られるような優先順位のドメインとアルゴリズムである。

本研究では、新たなマッチングメカニズム「DAPL with Minimum Quotas and Type-Specific Floors under Hierarchical Types（DAPLF）」を提案する。DAPLFは、Tomoeda（2018）が提案した「Deferred Acceptance Mechanism with Precedence Lists (DAPL)」を拡張したメカニズムである。DAPLFは、Tomoeda（2018）のアイデアを受け継ぎ、実現可能性、非浪費性、およびグループ耐戦略性を満たす。さらに、Tomoeda（2018）が提案した「B-common priority」と呼ばれる、実行可能性と公平性が両立するための十分条件を、本研究の枠組みで導出し、この条件下では、DAPLFは上述の性質に加え、公平性も達成する。

場所：2号館11階経済学部会議室B

Venue: 11th Floor, Bldg. No.2 Meeting Room B 

幹事/Organizer：長谷部拓也/Takuya Hasebe

言語/Language：英語/English

要旨/Abstract: Contract farming—agreements between farmers and buyers on agricultural production—often faces the challenge of contractual default because neighboring farmers may share information on more attractive price offers from non-contract buyers and coordinate actions to side-sell contract crops. This paper examines neighborhood effects on contractual enforcement in contract farming of organic Kampot pepper, a high-value crop in Cambodia. Using a spatial econometric framework, we demonstrate that side-selling by neighboring farmers significantly increases the probability of individual farmers engaging in side-selling, reflecting positive neighborhood effects. To clarify the underlying mechanisms, we develop a simple theoretical model of neighborhood effects. Our findings underscore the need for policy interventions aimed at curbing the diffusion of side-selling and strengthening the institutional sustainability of contract farming arrangements. 

場所：2号館11階経済学部会議室B

Venue: 11th Floor, Bldg. No.2 Meeting Room B 

幹事/Organizer：長谷部拓也/Takuya Hasebe & 橋立洋祐/Yosuke Hashidate

言語/Language：英語/English

要旨/Abstract: How does signal space size affect demand for information? We run laboratory experiments where signals vary in cardinality but hold instrumental value constant under expected utility. In our main setting, subjects purchase signals revealing which state determines the outcome of a compound lottery, and willingness to pay rises with signal space size—contradicting expected utility theory. Robustness tests show bids track instrumental value when it varies,ruling out misunderstanding. In another setting where lotteries include a free signal, valuations no longer increase with space size. We propose an entropy-based framework where people derive non-instrumental utility from uncertainty reduction, reflecting curiosity-driven motives.

場所：2号館11階経済学部会議室B

Venue: 11th Floor, Bldg. No.2 Meeting Room B 

幹事/Organizer：長谷部拓也/Takuya Hasebe 

言語/Language：英語/English

要旨/Abstract: This paper presents evidence from a randomized controlled trial evaluating a bundled digital intervention combining weather index insurance, localized weather forecasts, and agricultural extension services delivered via SMS to smallholder maize farmers in southern Mali. The study analyzes data from approximately 1,500 maize farming households across diverse agro-climatic zones and finds that the intervention generates economically and statistically significant improvements in farming practices, leading to substantial increases in maize yields and farm income. These effects are driven by better-informed decision-making enabled by timely and relevant weather information and agronomic advice, which induces adjustments in input use. A cost-benefit analysis indicates that the intervention is highly cost-effective. We discuss implications for scaling digital agricultural services in low-income settings and highlight avenues for future bundles.