2025.7.8
OSIPP基幹講座教員の6月の研究業績をご紹介します。
・丸山士行 先生 ・宮野紗由美 先生
・川窪悦章 先生 ・大久保邦彦 先生
・瀧井克也 先生
Shiko Maruyama （論文）
Fujimoto, Ayame, Rong Fu, Haruko Noguchi, Shiko Maruyama, Sayaka Nakamura (2025) “Breaking Brand: An Observational Study on Pharmacy-Hospital-Patient Relationships and Generic Drug Utilisation in Japan,” BMJ Open, 15(5). May, 2025（査読あり）
https://bmjopen.bmj.com/content/15/5/e093601
Abstract: ウェブリンクでご確認ください
Shiko Maruyama （論文）
Bai, Yuting, Shiko Maruyama, Si Wang (2025) “Nonlinear Relationship between the Number of Children and Late-Life Cognition,” China Economic Review, 91. June 2025,（査読あり）
https://www.sciencedirect.com/science/article/pii/S1043951X25000756
Abstract: Late-life cognition is a growing concern as populations age. This study investigates how the number of children affects late-life cognition in rural China by exploiting the exogenous variation in the rollout timing of Family Planning Policies. Theoretical analysis suggests a nonlinear effect along the fertility dimension. Using data from the China Health and Retirement Longitudinal Study, we find nonlinear causal effects of fertility. Having one more child when the mother has 4+ children leads to adverse effects on a range of late-life cognition measures, while positive effects exist for episodic memory and mental intactness at low parities, implying hump-shaped effect heterogeneity. Underlying this hump-shaped causal relationship is increased interaction with children but a greater risk of chronic conditions.
Shiko Maruyama （論文）
Maruyama, Shiko, Sayaka Nakamura (2025) “Wholesome Lunch to the Whole Classroom: Short- and Longer-Term Effects on Early Teenagers’ Weight,” Health Economics, 34(7), 1255-1273. July 2025（査読あり）
https://onlinelibrary.wiley.com/doi/10.1002/hec.4959
Abstract: Previous studies on the effect of school lunch programs on child obesity have been hampered by effect heterogeneity, self-selection, and stigma-induced under-reporting, having produced mixed findings. Its potential long-lasting effect has also been debated. We study the body-weight effect of a Japanese school lunch program, which provides nutritional lunch to all students at participating municipal junior highs. The lack of means testing and individual participation choice offers causal estimates of actual participation for a diverse and representative group of children. By exploiting almost universal school lunch coverage for elementary school children nationwide, we construct a difference-in-differences (DID) framework. Using the 1975–1994 National Nutrition Survey, a nationally representative household survey with measured height and weight, we find a regressive benefit of school lunch: while no statistically significant effect is found for the full sample, we find significant obesity-reducing effects for the subsamples of children with low socioeconomic backgrounds. This obesity-reducing effect remains at least a few years after graduation, implying effect through not only nutritional contents but also guiding healthy eating behavior. We find little evidence that school lunch reduces underweight. Propensity score weighting, the DID analysis for percentiles, and various falsification tests confirm the robustness of our estimates.
Sayumi Miyano （論文）
Li, Jialu and Sayumi Miyano (2025) “Mutual Gains or Exclusive Contests?: The Strategic Calculus of Japanese Firms on China’s CPTPP Bid”, Law & Geoeconomics, Published online: 28 May 2025（査読あり）
https://doi.org/10.1163/29505720-bja00001
Abstract: Firms today must assess the impact of new trade policies within a complex global business landscape shaped by expanding global value chains and geopolitical risks. How do they respond to new trade policies under discussion? We argue that firms take informational cues from other firms in the same industry and along their supply chains. We test this through a survey experiment with Japanese firm managers, examining their reactions to China’s potential entry into the Comprehensive and Progressive Agreement for the Trans-Pacific Partnership. Our findings show that positive views from large co-industry firms and supply chain partners lead to negative assessments by managers, not only among small firms but also among large exporting firms, driven by fears of rising domestic competition. Concerns also extend to the broader national economic impact. The study contributes to our understanding of the micro-foundations of trade politics, highlighting firm heterogeneity in their response to multifaceted trade policies.
川窪悦章 （論文）
「統計から見る経済安全保障」統計 第76巻第5号（2025年5月号）
https://jstat.stores.jp/items/6811a19e544a4b2b58b57692
概要：経済安全保障の問題に関して、マクロレベルのさまざまな統計を紹介するとともに、サプライチェーンの脆弱性に関する最新のミクロ実証研究をまとめている。
大久保邦彦 （判例批評）
「旧優生保護法の優生規定の違憲性と国賠請求の期間制限」民商法雑誌、第161巻第2号（2025年6月号）
https://www.yuhikaku.co.jp/static/minshoho.html
概要：「障害者に不妊手術を強制する旧優生保護法の各規定の内容は、日本国憲法１３条及び１４条１項により保障されている権利を違法に侵害するものであることが明白であったというべきであるから、同規定に係る国会議員の立法行為は、国家賠償法１条１項の適用上、違法であり、これに基づく損害賠償請求権の行使に対し国が除斥期間の主張をすることは、信義則に反し、権利の濫用として許されない。」（TKCの要旨）とした最高裁判決（最大判令和６・７・３民集78巻3号382頁）の判例批評
Katsuya Takii （Discussion Paper）
Tomoharu Mori and Katsuya Takii “The Effect of Coarse Score Labels on College Application Decisions” OSIPP Discussion Paper, DP-2025-E-002, June 6, 2025
https://hdl.handle.net/11094/101440
Abstract: This study examines whether people are inattentive to once-in-a-lifetime events. Using data from Japanese entrance examinations, we show that, even in situations where there appears to be little difference in the actual admissions probability, students change their school of choice simply because the coarse label describing admissions probability has changed. To understand the mechanism behind this result, we model students’ application decisions by incorporating inattention. The results suggest that, in once-in-a-lifetime situations, students do observe information more carefully than usual, but they still cannot be completely attentive. We also find that people with better information processing skills and who are accustomed to processing more information daily pay greater attention to information.