Economics

Working Papers

Encouraging Renewable Investment: Risk Sharing Using Auctions
Renewable energy projects face substantial risk because they sell their electricity into volatile wholesale electricity markets. Policymakers looking to encourage renewable investment can choose between power purchase agreements that assume investors’ risk of future electricity sales and generation subsidies that let investors take the risk. The relative value of these two approaches depends critically upon investors’ risk premium. This paper investigates this trade-off in the context of Brazilian wind energy actions that award winners purchase agreements for a share of their production. I develop and estimate a structural auction model that separately recovers the investors’ wholesale market beliefs, consisting of the expected price and risk premium, and private costs. The policymaker is expected to save $4.4 billion by taking the entire risk of enticing investors to install wind turbines that cost $12.2 billion. However, the policymaker must bear all future wholesale market risk over 20 years.

Identification and Estimation of Dynamic Games with Unknown Information Structure
(with Yuki Ito and Paul Koh)
This paper studies the identification and estimation of dynamic games when the underlying information structure is unknown to the researcher. To tractably characterize the set of Markov perfect equilibrium predictions while maintaining weak assumptions on players’ information, we introduce Markov correlated equilibrium, a dynamic analog of Bayes correlated equilibrium. The set of Markov correlated equilibrium predictions coincides with the set of Markov perfect equilibrium predictions that can arise when the players can observe more signals than assumed by the analyst. Using Markov correlated equilibrium as the solution concept, we propose tractable computational strategies for informationally robust estimation, inference, and counterfactual analysis that deal with the non-convexities arising in dynamic environments. We use our method to analyze the dynamic competition between Starbucks and Dunkin’ in the US and the role of informational assumptions.

Work in Progress

Primary Care Physician-Specialist Racial Concordance in Forming Referral Networks
(with Yuki Ito)
We study the role of racial concordance between primary care physicians and specialists in physician referral network formation and its consequences on racial health disparity. Using a 20% random sample of Medicare beneficiaries in the United States, we find that primary care physicians refer patients to the same race specialists more than otherwise, especially when the patients are also the same race. We propose a structural framework to separately identify the racial concordance effect net of health outcome benefits on referral decisions and the racial concordance effect on health outcomes.

Regulating Power Plant Emissions: Environmental Justice, Enforcement, and Regulator Preferences
(with Gautam Gowrisankaran and Ashley Langer)
We develop a structural framework of the interplay between the regulator and coal power plants in the context of dynamic enforcement. Plants invest in pollution abatement technologies in response to the regulator’s dynamic enforcement decisions. The regulator faces the trade-off between pollution and fines because heavy fines reduce pollution but harm the local economy. We estimate the regulator’s utility function, formulated as the weighted sum of the disutility from pollution and fines, along with the plants’ dynamic investment decision model. We use the model to evaluate how enforcement decisions affect the welfare of minority and low-income communities.

Published Papers

The Effect of Inertia on Brand-Name versus Generic Drug Choices
(with Yuki Ito and Yasuki Kobayashi) Journal of Economic Behavior & Organization, 172, 364–379, April, 2020.

Public Health and Clinical Research

Selected Papers

Heterogeneous Treatment Effect of Dose‐Dense Paclitaxel Plus Carboplatin Therapy for Advanced Ovarian Cancer. International Journal of Cancer, pages 1–10, 2024.
Ayumi Taguchi, Kosuke Kato, Akiko Furusawa, Konan Hara, Kenbun Sone, Kyosuke Yamada, Hiroaki Kajiyama, Muneaki Shimada, and Aikou Okamoto.

Prognosis of High‐Risk Human Papillomavirus‐Related Cervical Lesions: A Hidden Markov Model Analysis of a Single‐Center Cohort in Japan. Cancer Medicine, 11(3), 664–675, 2022.
Ryo Ikesu, Ayumi Taguchi, Konan Hara (Co-corresponding Author), Kei Kawana, Tetsushi Tsuruga, Jun Tomio, and Yutaka Osuga.

Claims-Based Algorithms for Common Chronic Conditions Were Efficiently Constructed Using Machine Learning Methods. PLOS ONE, 16(9), e0254394, 2021.
Konan Hara, Yasuki Kobayashi, Jun Tomio, Yuki Ito, Thomas Svensson, Ryo Ikesu, Ung-il Chung, and Akiko Kishi Svensson.

Radiation Therapy and the Risk of Herpes Zoster in Patients with Cancer. Cancer, 126(15), 3552–3559, 2020.
Takuya Shimizuguchi, Noritaka Sekiya, Konan Hara, Ayumi Taguchi, Yujiro Nakajima, Yu Miyake, Yukiko Shibata, Kentaro Taguchi, Hiroaki Ogawa, Kei Ito, and Katsuyuki Karasawa.

Heterogeneous Impact of Cytomegalovirus Reactivation on Nonrelapse Mortality in Hematopoietic Stem Cell Transplantation. Blood Advances, 4(6), 1051–1061, 2020.
Satoshi Kaito, Yujiro Nakajima, Konan Hara, Takashi Toya, Tetsuya Nishida, Naoyuki Uchida, Junichi Mukae, Takahiro Fukuda, Yukiyasu Ozawa, Masatsugu Tanaka, Kazuhiro Ikegame, Yuta Katayama, Takuro Kuriyama, Junya Kanda, Yoshiko Atsuta, Masao Ogata, Ayumi Taguchi, and Kazuteru Ohashi.

Multistate Markov Model to Predict the Prognosis of High-Risk Human Papillomavirus-Related Cervical Lesions. Cancers, 12(2), 270, 2020.
Ayumi Taguchi, Konan Hara, Jun Tomio, Kei Kawana, Tomoki Tanaka, Satoshi Baba, Akira Kawata, Satoko Eguchi, Tetsushi Tsuruga, Mayuyo Mori, Katsuyuki Adachi, Takeshi Nagamatsu, Katsutoshi Oda, Toshiharu Yasugi, Yutaka Osuga, and Tomoyuki Fujii.

Association Measures of Claims-Based Algorithms for Common Chronic Conditions Were Assessed Using Regularly Collected Data in Japan. Journal of Clinical Epidemiology, 99, 84–95, 2018.
Konan Hara, Jun Tomio, Thomas Svensson, Rika Ohkuma, Akiko Kishi Svensson, and Tsutomu Yamazaki.

Other Papers

Increased Risk of Placenta Previa and Preterm Birth in Pregnant Women With Endometriosis/Adenomyosis: A Propensity‐Score Matching Analysis of a Nationwide Perinatal Database in Japan. Journal of Obstetrics and Gynaecology Research, 50(3):351–357, 2024.
Kosuke Kato, Takayuki Iriyama, Konan Hara, Kensuke Suzuki, Ayako Hashimoto, Seisuke Sayama, Mari Ichinose, Masatake Toshimitsu, Takahiro Seyama, Kenbun Sone, Keiichi Kumasawa, Takeshi Nagamatsu, Yasushi Hirota, Kaori Koga, and Yutaka Osuga.

Heterogeneous Effects of Cytotoxic Chemotherapies for Platinum-Resistant Ovarian Cancer. International Journal of Clinical Oncology, 28(9), 1207–1217, 2023.
Katsuhiko Nara, Ayumi Taguchi, Takehito Yamamoto, Konan Hara, Yuri Tojima, Harunori Honjoh, Akira Nishijima, Satoko Eguchi, Yuichiro Miyamoto, Kenbun Sone, Mayuyo Mori, Tappei Takada, and Yutaka Osuga.

Heterogeneous Treatment Effects of Adjuvant Therapy for Patients with Cervical Cancer in the Intermediate‐Risk Group. Cancer Medicine, 12(18), 18557–18567, 2023.
Ayumi Taguchi, Kosuke Kato, Konan Hara, Akiko Furusawa, Yujiro Nakajima, Chihiro Ishizawa, Michihiro Tanikawa, Kenbun Sone, Mayuyo Mori, Muneaki Shimada, Aikou Okamoto, and Munetaka Takekuma.

Gestational Stage-Specific Association of Hemoglobin Concentration with the Risk of Preterm Birth and Small for Gestational Age. Hypertension Research in Pregnancy, 11(2), 25–35, 2023.
Masatake Toshimitsu, Norikazu Ueki, Konan Hara, Jun Takeda, Shintaro Makino, Kosuke Kato, Keiichi Kumasawa, Takayuki Iriyama, Takeshi Nagamatsu, and Yutaka Osuga.

Impact of Lung Function Impairment after Allogeneic Hematopoietic Stem Cell Transplantation. Scientific Reports, 12(1), 14155, 2022.
Yuya Kishida, Naoki Shingai, Konan Hara, Makiko Yomota, Chika Kato, Satoshi Sakai, Yasuhiro Kambara, Yuya Atsuta, Ryosuke Konuma, Atsushi Wada, Daisuke Murakami, Shiori Nakashima, Yusuke Uchibori, Daishi Onai, Atsushi Hamamura, Akihiko Nishijima, Takashi Toya, Hiroaki Shimizu, Yuho Najima, Takeshi Kobayashi, Hisashi Sakamaki, Kazuteru Ohashi, and Noriko Doki.

Acceptance, Barriers, and Facilitators to Implementing Artificial Intelligence–Based Decision Support Systems in Emergency Departments: Quantitative and Qualitative Evaluation. JMIR Formative Research, 6(6), e36501, 2022.
Ryo Fujimori, Keibun Liu, Shoko Soeno, Hiromu Naraba, Kentaro Ogura, Konan Hara, Tomohiro Sonoo, Takayuki Ogura, Kensuke Nakamura, and Tadahiro Goto.

Adherence to Daily, Weekly, and Monthly Dosing Regimens of Bisphosphonates for Osteoporosis Treatment in Postmenopausal Women in Japan: A Retrospective Study Using Claims Data. The Tohoku Journal of Experimental Medicine, 255(2), 147–155, 2021.
Yuki Kosaka, Takehiro Sugiyama, Konan Hara, and Yasuki Kobayashi.

Knowledge, Experience, and Perceptions of Generic Drugs among Middle-Aged Adults and Their Willingness-to-Pay: A Nationwide Online Survey in Japan. The Tohoku Journal of Experimental Medicine, 255(1), 9–17, 2021.
Yuki Ito, Konan Hara, Hajime Sato, and Jun Tomio.

Clinical Performance of Early Warning Scoring Systems for Identifying Sepsis among Anti-hypertensive Agent Users. The American Journal of Emergency Medicine, 48, 120–127, 2021.
Itsuki Osawa, Tomohiro Sonoo, Shoko Soeno, Konan Hara, Kensuke Nakamura, and Tadahiro Goto.

Association of Initial Potassium Levels with the Type of Stroke in the Emergency Department. Journal of Stroke and Cerebrovascular Diseases, 30(8), 105875, 2021.
Kiyomitsu Fukaguchi, Hiroshi Yamagami, Shoko Soeno, Konan Hara, Toru Shirakawa, Tomohiro Sonoo, Kensuke Nakamura, and Tadahiro Goto.

Initial Assessment in Emergency Departments by Chief Complaint and Respiratory Rate. Journal of General and Family Medicine, 22(4), 202–208, 2021.
Shoko Soeno, Konan Hara, Ryo Fujimori, Katsuhiko Hashimoto, Toru Shirakawa, Tomohiro Sonoo, Kensuke Nakamura, and Tadahiro Goto.

Validation of Chief Complaints, Medical History, Medications, and Physician Diagnoses Structured with an Integrated Emergency Department Information System in Japan: The Next Stage ER System. Acute Medicine & Surgery, 7(1), 1–8, 2020.
Tadahiro Goto, Konan Hara, Katsuhiko Hashimoto, Shoko Soeno, Toru Shirakawa, Tomohiro Sonoo, and Kensuke Nakamura.

Clinical Outcomes in Donors and Recipients of Kidney Transplantations Involving Medically Complex Living Donors – A Retrospective Study. Transplant International, 33(11), 1417–1423, 2020.
Yoshitaka Kinoshita, Takashi Yagisawa, Toru Sugihara, Konan Hara, Saki Takeshima, Taro Kubo, Takahiro Shinzato, Toshihiro Shimizu, Michiko Suzuki, Akito Maeshima, Jun Kamei, Akira Fujisaki, Satoshi Ando, Motofumi Suzuki, Haruki Kume, and Tetsuya Fujimura.

Differential Expression of Human Papillomavirus 16-, 18-, 52-, and 58-Derived Transcripts in Cervical Intraepithelial Neoplasia. Virology Journal, 17(1), 32, 2020.
Satoshi Baba, Ayumi Taguchi, Akira Kawata, Konan Hara, Satoko Eguchi, Mayuyo Mori, Katsuyuki Adachi, Seiichiro Mori, Takashi Iwata, Akira Mitsuhashi, Daichi Maeda, Atsushi Komatsu, Takeshi Nagamatsu, Katsutoshi Oda, Iwao Kukimoto, Yutaka Osuga, Tomoyuki Fujii, and Kei Kawana.

Postradiotherapy Persistent Lymphopenia as a Poor Prognostic Factor in Patients with Cervical Cancer Receiving Radiotherapy: A Single-Center, Retrospective Study. International Journal of Clinical Oncology, 25(5), 955–962, 2020.
Ayumi Taguchi, Akiko Furusawa, Kei Ito, Yujiro Nakajima, Takuya Shimizuguchi, Konan Hara, Maki Takao, Tomoko Kashiyama, Nao Kino, Katsuyuki Karasawa, and Toshiharu Yasugi.

Can Income-Based Co-payment Rates Improve Disparity? The Case of the Choice between Brand-Name and Generic Drugs. BMC Health Services Research, 19(1), 780, 2019.
Yuki Ito, Konan Hara, Byung-kwang Yoo, Jun Tomio, and Yasuki Kobayashi.

Plasma Cell Neoplasm as a Risk Factor for Early Thrombosis of Arteriovenous Fistula. Hemodialysis International, 22(2), 176–179, 2018.
Yoshitaka Kinoshita, Akira Ishikawa, Konan Hara, Toru Sugihara, Yoshitaka Ishibashi, and Yukio Homma.