Ibuka, Yoko

写真a

Affiliation

Faculty of Economics ( Mita )

Position

Professor
Scopus Paper Info  
Paper Count: 39 Citation Count: 914 h-index: 14

Click to view the Scopus page. The data was downloaded from Scopus API in March 15, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Career 【 Display / hide 】

  • 2008.07
    -
    2011.03

    Yale University, School of Public Health, Postdoctoral Associate / Postdoctoral Fellow

  • 2011.04
    -
    2012.07

    Hitotsubashi University, Graduate School of Economics, Assistant Professor

  • 2012.08
    -
    2013.03

    Kyoto University, Graduate Schoole of Pharmaceutical Sciences, Specially Appointed Associate Professor

  • 2013.04
    -
    2016.03

    Tohoku University, Graduate School of Economics, Associate Professor

  • 2016.04
    -
    2019.03

    Keio University, Department of Economics, Associate Professor

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Papers 【 Display / hide 】

  • The impact of reducing formal care benefits on caregivers’ well-being: evidence from Japan

    Fu R., Le D.D., Ibuka Y.

    Review of Economics of the Household 23 ( 4 ) 1221 - 1249 2025.12

    ISSN  15695239

    　View Summary

    This study examines the impact of reducing formal care benefits on the well-being of informal caregivers, contributing to the ongoing discourse about establishing sustainable and adequate levels of formal care. We utilize a reform introduced in Japan’s public long-term care insurance system, which curtailed formal care benefits for a group of recipients with low care needs. Employing a difference-in-difference approach with fixed effects on a nationally representative sample of coresident informal caregivers, we explore both the overall and temporal effects of this reform. Our findings reveal that the reform had an adverse impact on caregivers’ physical well-being, leading to diminished mobility and stability. The impact on caregivers’ mental well-being was less clear, reflecting a competing influence of stress and the psychological rewards associated with caregiving. The decline in physical well-being endured over time, while the effects on mental well-being were transient. Additionally, female caregivers exhibited greater vulnerability compared to their male counterparts, experiencing more significant deterioration in both physical and mental well-being. Alarmingly, the reform also negatively influenced the well-being of care recipients, suggesting that reducing formal care benefits does not yield positive outcomes for either caregivers or recipients. This study underscores the necessity of accounting for caregivers’ well-being when evaluating the cost-effectiveness of reducing formal care benefits and advocates for policies aimed at safeguarding female caregivers from health and financial challenges.

  • The intergenerational health effects of child marriage bans

    Le D.D., Molina T., Ibuka Y., Goto R.

    Journal of Health Economics 104 2025.12

    ISSN  01676296

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    Using data from 17 countries, we investigate the effects of child marriage bans on child mortality in the next generation. We use within-country variation in mothers’ exposure to the ban across cohorts and in “treatment intensity,” calculated based on region-level child marriage prevalence and marriage age prior to the ban. We find that child marriage bans reduced under-5 mortality, with an effect of 19.7 percent corresponding to a one standard deviation change in treatment intensity. Increases in age at first marriage and first birth, which may have led to improved health-related decisions around the time of birth, appear to be the main drivers of the mortality reductions documented.

  • Continuing to be cautious: Japanese contact patterns during the COVID-19 pandemic and their association with public health recommendations

    Nakamura T., Kinoshita R., Endo A., Atkins K.E., Oshitani H., Ibuka Y., Suzuki M., Ariyoshi K., O’Reilly K.M.

    Plos Global Public Health 5 ( 9 September )  2025.09

    　View Summary

    Despite implementing no lockdowns and having a large elderly population, Japan had a low mortality rate due to COVID-19 compared to Europe and North America. The extent to which policies impacted person-to-person contact remains unclear. In this study, we examined changes in contact patterns and their association with behaviors and governmental recommendations in Japan during the pandemic. Ten social contact surveys were conducted between 2021 and 2023 reaching over 1500 participants per survey in Osaka and Fukuoka prefectures where governmental recommendations were first implemented due to high COVID-19 incidence. Their contact patterns were assessed through their demographic characteristics, COVID-19 vaccination status, and individual disease mitigation measures. Generalized linear models were used to identify factors associated with increased contacts. The mean number of contacts during the pandemic declined by at least 49.8% (8.2 weekday contacts and 6.0 weekend contacts per individual, adjusted by age and sex) compared to a study conducted prior to 2020. Weekdays, occupation, larger household sizes, and mask wearing were associated with a higher number of contacts. The frequency and duration of contacts were negatively associated with the issuance of COVID-19 governmental measures, yet the relative change in contacts was not as prominent as pre- and post-lockdown situations in the United Kingdom. There was a gradual increase in contacts with time and less strict public health recommendations. Yet, contacts that did not increase with uptake of COVID-19 vaccination and continuous mask wearing depict cautious behavior across the survey population during the pandemic and into 2023. These results are in contrast with European countries where contacts largely increased among vaccinated individuals compared to the non-vaccinated. Social contacts are country and context specific, highlighting the need for data collection across different communities.

  • Public investment on health and voter responses: Evidence from the mass vaccination during COVID-19

    Takahashi M., Takaku R., Ashida T., Ibuka Y.

    European Journal of Political Economy 89 2025.09

    ISSN  01762680

    　View Summary

    This study examines the effect of COVID-19 vaccination on political support by leveraging Japan's age-based vaccination rollout, which prioritized people aged 65 and older. Using a fuzzy regression discontinuity design, we found that vaccination increased favorable opinions of vaccination progress and infection control measures by 27.4% and 14.7%, respectively. These favorable opinions extended to positive perceptions of other infection control measures, ultimately fostering trust in the government. In addition, the effect of vaccination was heterogeneous: it was more pronounced among individuals with chronic diseases, women, those of lower socioeconomic status, and those with higher levels of interpersonal trust. In contrast, low trusters became more dissatisfied with how the Tokyo Olympics and Paralympics in 2021 were managed, without showing an increase in positive opinions of the government.

  • Income receipt, economic activities, and health: Evidence from ambulance transport patterns

    Ibuka Y., Hamaaki J.

    Journal of Health Economics 100 2025.03

    ISSN  01676296

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    Studies indicate that mortality increases after income receipt. To explore whether this is due to increased economic activity around the period of receiving income, we examine within-month patterns in ambulance transport incidents, focusing on location and timing. Using Japan's National Pension payments made every two months, we compare the number of ambulance transport incidents on the day of pension payment and on surrounding days in payment months with those in non-payment months. The results show a 4.5% increase in ambulance transport incidents on the day of pension payment, linked to increased activities such as gambling, shopping, and dining out. We show suggestive evidence that income receipt boosts economic activities by the mechanism of easing liquidity constraints. These findings have implications for healthcare system preparedness and the optimal design of public benefit payment.

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

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • 高頻度記録データを用いた公共政策の効果分析：健康・消費・犯罪に対する影響

    2024.04
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    2028.03

    基盤研究(B), Principal investigator

  • Income receipt and health: causal effect in the short run and the long run

    2020.04
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    2024.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

  • 景気変動が健康の水準と格差に与える影響とそのメカニズム

    2016.04
    -
    2019.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

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Courses Taught 【 Display / hide 】

  • TOPICS IN APPLIED ECONOMICS AND POLICY

    2025

  • SEMINAR: SOCIAL POLICY

    2025

  • SEMINAR: APPLIED ECONOMICS AND POLICY

    2025

  • SEMINAR: APPLIED ECONOMICS

    2025

  • SEMINAR IN SPECIAL TOPICS B

    2025

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