## 大阪大学経済学研究会

## GSE-OSIPP joint seminars in economics

## IPP研究会共催

## NEW■2024年度 第2回 大阪大学経済学研究会 のご案内（IPP研究会共催）

日時：2024年5月23日（木）13時30分～15時00分

会場: 国際公共政策研究科棟6階会議室

講師：Shurojit Chatterji氏（Singapore Management University）

タイトル："Efficiency with Heterogenous forecasts"

アブストラクト：Do price forecasts of rational economic agents need to coincide in intertemporal perfectly competitive complete markets in order for markets to allocate resources efficiently? Recent work in a two-period model with a nominal bond has shown that there is a one dimensional set of efficient allocations for generic endowments that can be sustained by heterogenous forecasts. Moreover, these efficient allocations can be supported by forecasts that disagree up to one degree of freedom. Thus, strong as efficiency and perfect competition may appear, they do not imply perfect foresight, but they do add explanatory power to temporary equilibrium, since they select a small subset out of the Pareto efficient allocations, which generally have higher dimension. We next study a muti-period model with a nominal bond that matures in one period and identify the set of efficient allocations that can be sustained as Walrasian equilibria with heterogenous forecasts. We then add a long maturity bond, which under perfect foresight would be a redundant asset, and show that it fundamentally expands the set of efficient allocations that can be sustained as Walrasian equilibria. Indeed all wealth transfers compatible with efficiency can arise endogenously. The key feature driving this conclusion are forecasting errors, which lead to ex post arbitrage opportunities that induce these income transfers.

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Time and Date : Thursday, May 23rd, 2024

Seminar Venue: The Conference Room on the 6th floor of OSIPP in Toyonaka Campus

Speaker: Shurojit Chatterji氏（Singapore Management University）

Title : "Efficiency with Heterogenous forecasts"

Abstract: Do price forecasts of rational economic agents need to coincide in intertemporal perfectly competitive complete markets in order for markets to allocate resources efficiently? Recent work in a two-period model with a nominal bond has shown that there is a one dimensional set of efficient allocations for generic endowments that can be sustained by heterogenous forecasts. Moreover, these efficient allocations can be supported by forecasts that disagree up to one degree of freedom. Thus, strong as efficiency and perfect competition may appear, they do not imply perfect foresight, but they do add explanatory power to temporary equilibrium, since they select a small subset out of the Pareto efficient allocations, which generally have higher dimension. We next study a muti-period model with a nominal bond that matures in one period and identify the set of efficient allocations that can be sustained as Walrasian equilibria with heterogenous forecasts. We then add a long maturity bond, which under perfect foresight would be a redundant asset, and show that it fundamentally expands the set of efficient allocations that can be sustained as Walrasian equilibria. Indeed all wealth transfers compatible with efficiency can arise endogenously. The key feature driving this conclusion are forecasting errors, which lead to ex post arbitrage opportunities that induce these income transfers.

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## ■今後のスケジュール

日時：2024年5月30日（木）13：30～15：00

会場：豊中キャンパス国際公共政策研究科6階会議室

講師：小西 秀男氏（Boston College）

タイトル：Competing Teams in Large Markets: Free Entry Equilibrium with (Sub-)Optimal Contracts

アブストラクト：In this paper, we formalize a market with a large number of competing production teams following Alchian and Demsetz (1974). We allow for wide-spread externalities which can affect players’ payoffs. These externalities include changes in market conditions and pollutions, and may generate a variety of equilibrium outcomes. There are finite types of atomless players, who can form team-firms with finite memberships using available technologies. Given an arbitrary set of feasible partnership contracts for each team type, we consider free entry equilibrium as our equilibrium concept—in a free entry equilibrium, no team type can attract its members from other teams by proposing any implementable partnership contract. Furthermore, in a free entry equilibrium, players of the same type may have different payoffs—unequal treatment of equals. We show that as long as each firm type’s implementable payoff set is compact and continuous in externality variables, there exists a free entry equilibrium. We provide several applications of our results.

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日時：2024年6月6日（木）13：30～15：00

会場：豊中キャンパス国際公共政策研究科6階会議室

講師：Hyunseok Jung氏（University of Arkansas）

タイトル：Testing for Peer Effects without Specifying the Network Structure

アブストラクト：This paper proposes an Anderson-Rubin (AR) test for the presence of peer effects in panel data without the need to specify the network structure.The unrestricted model of our test is a linear panel data model of social interactions with dyad-specific peer effects. The proposed AR test evaluates if the peer effect coefficients are all zero. As the number of peer effect coefficients increases with the sample size, so does the number of instrumental variables (IVs) employed to test the restrictions under the null, rendering Bekker’s many-IV environment. By extending existing many-IV asymptotic results to panel data, we establish the asymptotic validity of the proposed AR test. Our Monte Carlo simulations show the robustness and superior performance of the proposed test compared to some existing tests with misspecified networks. We provide two applications to demonstrate its empirical relevance. After the seminar on June 6, I will move to Tokyo (using Shinkansen), where I will give a seminar at the U of Tokyo on June 7. If your department can reimburse the train cost for me, that would be great! For your reference, below items will be reimbursed from the U of Tokyo:

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日時：2024年6月27日（木）13:30～15：00

会場：TBA

講師：佐野 隆司氏（横浜国立大学）

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【マクロ研共催セミナー】

日時：2024年7月19日（金）13:30～

会場：豊中キャンパス法経講義棟7階 大会議室

講師：13:30-15:00 稲垣 一真氏（ロチェスター大学）/ 15:20-16:50 保里 俊介氏（一橋大学）

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日時：2024年７月25日（木）13:30～16：40

会場：TBA

講師：守屋 隆弘氏（Stony Brook University）土居 直史氏（小樽商科大学）

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日時：2024年8月1日（木）13：30～15：00（調整中）

会場：TBA

講師：能勢 学氏（IMF）

## ■2024年度過去のセミナー

## 第1回 大阪大学経済学研究会

日時：2024年4月5日（金）16時50分～18時20分

会場: 国際公共政策研究科棟6階会議室

講師：Asad Islam 氏 (Monash University)

タイトル："Forced Displacement, Mental Health, and Child Development: Evidence from the Rohingya Refugees"

アブストラクト：Forced displacement is a major driver of mental disorders among refugees worldwide. Poor mental health of adult refugees, particularly mothers, is also considered a risk factor for the psychological well-being and development of their children. In this study, we experimentally examine the extent to which a multifaceted psychosocial program improves the mental health of refugee mothers, and facilitates growth and development among children under the age of two. In partnership with BRAC, we ran a cluster randomized controlled trial on 3,500 Rohingya mother-child dyads in refugee camps in Bangladesh. Participants were given weekly psychosocial support for 44 weeks through peer volunteers, which includes psychoeducation and parenting support for mothers and play activities for both mothers and children. The intervention was largely successful and led to: (i) reductions in the psychological trauma and depression severity of mothers and children, (ii) improvements in communication, gross-motor, and problem-solving skills of children, and (iii) reductions in stunting and severe stunting. The intervention cost about $1 per dyad per week and is currently being scaled up in refugee camps in Bangladesh, where about seventeen thousand mother-child pairs now benefit from it.