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Picture of Kazuki Motohashi

Kazuki Motohashi

School: Graduate School of Arts and Sciences, the Fletcher School

Department: Economics

Research Interests: Public Health, Business and Economics, Environmental Economics, Development Economics

TIE Affiliation

Environmental Research Fellowship


Open defecation remains a huge issue regardless of universal latrine coverage achieved in India. The low latrine usage is due to a lack of correct information on the cost and technology of latrine usage. This study examines the effectiveness of a solution to provide accurate information on emptying price and frequency of latrine pits. I use a randomized control trial to examine whether households who receive information on price and technology reduce the perceived usage cost and increase latrine usage. Furthermore, I examine how latrine usage behavior diffuses to a wider population through social networks and who are influential in spreading the behavior. Our approach to providing the information is cheaper and more scalable than other monetary interventions. Thus, the findings of this study help the policy stakeholders, including governments and NGOs, to design and implement an effective policy to achieve sustained latrine usage and eliminate open defecation.


Kazuki is a PhD candidate at the Fletcher School and Graduate School of Arts and Science in the Economics department. He expects to complete his studies in May 2023. Kazuki earned a Bachelor of Laws and Master of Public Policy from the University of Tokyo. Prior to coming to Tufts, he conducted research projects for Japanese governments in the field of environment and energy at the Mitsubishi Research Institute, which is a top public policy think tank in Japan. While he was working there for four years, Kazuki often visited Southeast Asian countries, especially Vietnam, for research projects on how to promote the introduction of Japanese water and wastewater treatment technologies to those countries. He had discussions with government agencies to understand their policies and regulations on water quality, and conduct field surveys to local factories and sewage treatment plants to examine their demand and constraints of introducing wastewater treatment technologies. Through these experiences, Kazuki became interested in water quality and sanitation issues in developing countries, which are current research topics at Tufts.

Current Studies and Future Goals

When asked what he found most meaningful about his field of study, Kazuki responded with the following: “I find Economics very helpful to analyze the constraints that households and firms face when they adopt environmental technologies (e.g., latrines, industrial wastewater treatment plants) and suggest effective government policies to promote the technology adoption for better environmental quality. For example, latrine adoption behavior can be modeled as comparing costs and benefits of latrine usage and open defecation. From this model, we can identify several constraints behind latrine usage, such as a financial constraint on latrine construction and information constraint on understanding the benefit of latrine usage. In addition, Economics has a lot of powerful tools to quantitatively examine the effectiveness of a policy, which is based on economic models. Thus, I am able to provide evidence-based solutions to environmental issues."

When asked what interested him in becoming a TIE Fellow, Kazuki responded with the following: "First, I was fascinated by the interdisciplinary nature of this TIE program. I look forward to exchanging ideas with fellows from various schools/departments in workshops and presentations. Second, my dissertation involves multiple large-scale field surveys on latrine usage in India. The funding of this TIE program allows me to complete these surveys."

After finishing his PhD here at Tufts, Kazuki hopes to continue empirical research on environmental issues in developing countries at academic institutions and international organizations.

Fun Facts!

Kazuki enjoys doing yoga to relax outside of schoolwork, and hope to become a yoga instructor on weekends.

Favorite food/drink: Taco, Pho, Sushi

Favorite movie/TV show: La La Land

Favorite song/artist: Maroon 5