Seongjoo Min

Network of Loyalty Programs: A Sequential Formation

By forming partnerships with hotel chains and airlines, major credit card issuers in the U.S. allow customers to transfer points from their loyalty programs to the partners'. Hotel chains form similar partnerships with airlines, and airlines with other airlines. Viewing their partnerships as a network and using a sequential network formation model, this article studies how credit card issuers and hotel chains strategically choose to add, delete, or maintain partnerships with airlines. Using a novel dataset that involves 3 credit card issuers, 7 hotel chains, and 43 airlines from 2014 to 2018, the estimation result suggests that a credit card issuer is more likely to form a partnership with an airline that (1) is a partner of another credit card issuer (2) is a partner of its hotel chain partner (3) better complements its existing portfolio of airline partners, after accounting for key characteristics of firms. The first two results are similar when hotel chains choose airline partners.

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Dyadic Regression with Block-Specific Fixed Effects and Application to Input-Output Matrix

Viewing the Input-Output matrix as a network of industries, this article studies how exogenous shocks, such as changes in tax rates and import duty rates, can affect relationships between industries within the U.S. economy. It also proposes a method for making counterfactual predictions on the Input-Output Matrix. A key innovation is utilizing a stochastic blockmodel to group industries into blocks, so that pairs of industries that belong to the same pair of blocks share common pairwise block-specific fixed effects. It uses dyadic regression model to estimate model parameters, together with pairwise block-specific fixed effects. An empirical analysis using the 2017 U.S. Input-Output Matrix shows that the supplier-buyer relationship between commodities (or industries) are sensitive to changes in net tax rates and import duty rates.

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Communities and Centralities of Supplier-Buyer Network of the U.S. Tech Sector

Analysis of the U.S. tech sector's supplier-buyer network shows a strengthening of ecosystems around major firms from 2003 to 2014. Community detection methods reveal four distinct ecosystems, each led by AAPL, DELL, IBM, and MSFT. Supplier-buyer interactions within each ecosystem is far greater than across ecosystems, indicating exclusivity in suppliers and buyers around each of the four firms. Moreover, the substantial growth of AAPL and MSFT's significance, or centrality, in the network and their ecosystems underscore their rising dominance within the U.S. tech sector.

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Courses at the University of Iowa

Bracket contains medians of [Organization, Clarity, Learning Focused, Learning Materials, Assessment, Support] reported in student course evaluation. Score ranges from 1 to 6, and higher is better.

Academic Year 2024-2025

• ECON:5800 Econometrics (first-year Ph.D. course)
  [N/A]

• ECON:4800 Econometric Analysis: Advanced Causal Inference with Data
  [5.5, 5, 6, 5.5, 6, 6]

• ECON:3300 Introduction to Econometrics: Causal Inference with Data
  [6, 6, 6, 5, 6, 6]

Academic Year 2023-2024

• ECON:5800 Econometrics (first-year Ph.D. course)
  [6, 6, 6, 6, 6, 6]

• ECON:3300 Introduction to Econometrics: Causal Inference with Data (two courses)
  [5, 6, 4, 4, 6, 6]

Academic Year 2022-2023

• ECON:5800 Econometrics (first-year Ph.D. course)
  [6, 6, 6, 6, 6, 6]

• ECON:3300 Introduction to Econometrics: Causal Inference with Data (two courses)
  [5.5, 5, 5.5, 6, 6, 6]

Academic Year 2021-2022

• ECON:5800 Econometrics (first-year Ph.D. course)
  [6, 6, 5.5, 6, 6, 6]

• ECON:3300 Introduction to Econometrics: Causal Inference with Data (two courses)
  [6, 5.5, 5.5, 5.5, 5.5, 6]

Academic Year 2020-2021

• ECON:5800 Econometrics (first-year Ph.D. course)
  [6, 5, 5, 5.5, 5.5, 6]

• ECON:3355 Economic and Business Forecasting
  [6, 5.5, 5.5, 6, 5.5, 6]

Selected Student Feedback (I really appreciate everyone who has taken my course!)

• "Professor Min is amazing! One of the best professors I have ever had at Iowa. Funny, well-spoken, and always highly focused on how he is conveying content."

• "Thanks for alway being available during office hours. Your jokes also made lecture much more enjoyable to be in."

• "You are a very great teacher and were always super helpful in office hours. It is clear that you love what you teach, which is exciting for a student."

• "This course was a great build-off of Stats for Business with lots of focus on how it would be applicable in the real world, so I really enjoyed the course. I could see myself using the things I learned in this course in the future at a firm, and I think the knowledge I gained from it will be valuable to me going forward."

• "The homework were well done and easy to follow. In previous courses in the department, using the statistical softwares on homework assignments was confusing and required me to put extra hours into correctly easy to explain mistakes. However, in this course, the homework was abundantly clear and super easy to follow along with. I learned more about the course from doing the homework and developed a better understanding of how I would use the course material in the real world."

• "When I had heard about econometrics from friends, I heard horror stories... but they did not have Dr. Min. This course has been so well taught and I really feel that I understand everything we learned this year. Dr. Min is what made this class so great for me."

• "Covering such a body of material in the limited time of the semester was extremely impressive. Explanations were extremely succinct, and it is evident that you are have an excellent understanding of theoretical econometrics."

• "Professor Min is probably the most willing and excited professor I have ever had to help students. Almost always he is able to answer student questions and is always willing to give guidance-- truly a professor who wants his students to succeed and do well in his class (which he knows can be challenging)."

• "I enjoyed the class, and Professor Min is an amazing Teacher who teaches so students can understand the material using simple words, unlike most teachers who make it harder to understand. He is always available during his office hours and willing to explain the material further."

• "I personally felt well-supported and respected."