Research

Published Papers

• Flexible Demand Estimation with Nonparametric Income Effect: An Application to Pass-Through and Merger Analysis. 2025 (with Yuta Toyama) Journal of Industrial Economics 73(1), 186–233. [Journal Link]
• Does Traditional Price Policy Work for Achieving Low Smoking Rate? – Empirical and Theoretical Evaluation Based on the United States Aggregate Data. 2020 (with Haruko Noguchi) Applied Economics, 52(18), 1986–1997. [Journal Link] (Based on my undergraduate senior thesis)
• Differences in Cancer Patients’ Work-cessation Risk, Based on Gender and Type of Job: Examination of Middle-aged and Older Adults in Super-aged Japan. 2020 (with Haruko Noguchi, Rong Fu, Cheolmin Kang, Akira Kawamura, Shinsuke Amano, and Atsushi Miyawaki) PLOS ONE, 15(1), e0227792. [Journal Link]
• How Do Cardiovascular Diseases Harm Labor Force Participation? Evidence of Nationally Representative Survey Data from Japan, a Super-aged Society. 2019 (with Rongu Fu, Haruko Noguchi, Cheolmin Kang, Akira Kawamura, Hideto Takahashi, Nanako Tamiya) PLOS ONE, 14(7), e0219149. [Journal Link]

Working Papers

• Disentangling Sources of Variation in C-Section Rates (with Stefanie Fischer, Heather Royer, and Corey White) [NBER]
  Abstract ▼
  Cesarean section rates vary widely across U.S. counties, yet it remains unclear how much of this variation reflects demand-side factors (such as patient risk or preferences) versus supply-side factors (such as physician practices or hospital incentives). We develop a new empirical strategy to isolate the influence of supply-side forces. Exploiting hospital obstetric unit closures from 1989–2019 that reallocate some mothers to counties with different C-section rates, we find that a one–percentage-point increase in the delivery county’s rate raises a mother’s likelihood of a C-section by roughly one point. The results point to a dominant role for provider behavior and local practice norms in driving geographic variation in C-section use, the most common major surgery in the United States.
• Heating Price and Infant Health [SSRN]
  — Revise and Resubmit at American Journal of Health Economics
  Abstract ▼
  This paper shows how the price of home heating can affect adverse birth outcomes when mothers are exposed to cold temperatures. To this end, I leverage geographical variation in the type of energy for home heating, temporal variation in natural gas prices triggered by the fracking boom, and seasonal variation in exposure to cold temperatures. Using U.S. birth records for 2001–2015, I find that higher home-heating prices increase the risk of serious conditions such as very preterm birth and very low birthweight when pregnant women are exposed to cold weather. A back-of-the-envelope calculation suggests that roughly 2\% of births with such severe conditions were avoided as a result of the decline in heating costs during the late-2000s fracking boom. As a potential mechanism, I examine how rising heating prices force households to reallocate spending. Although families may reduce heating use, the inelastic demand for heating implies that total energy expenditures still increase, leaving fewer resources for other goods. Consistent with this hypothesis, I find that higher energy prices raise household energy spending while reducing healthcare expenditures.

Work in Progress

• Fluoride at Low Doses: Dental Health and Adolescent Self-Esteem (with Cheolmin Kang)
  Abstract ▼
  While the benefits and risks of fluoride in drinking water remain central to public health debates, most evidence focuses on relatively high concentrations, often in the context of community water fluoridation. We estimate the causal effects of lower fluoride exposure by exploiting quasi-exogenous variation in naturally occurring fluoride concentrations shaped by regional geology in Japan. Combining longitudinal survey data, medical claims, and patient surveys, we find that fluoride substantially improves childhood dental health. Fluoride exposure also increases self-esteem among adolescent girls, primarily by reducing visible dental problems and improving appearance. We find no evidence of adverse effects on cognitive performance or educational attainment. These findings suggest that fluoride exposure within the low concentration range observed in our setting can yield meaningful dental and psychosocial benefits without detectable cognitive harm, implying that policies aimed at fully removing fluoride from drinking water may forgo important benefits.