I am an industrial organization economist working on platform markets and the “smart city”. I study e-commerce, transportation, and housing, often through the lens of empirical market design.
I am an Assistant Professor (Presidential Young Professor) at the Department of Strategy and Policy at the National University of Singapore (NUS) Business School.
Previously, I was a Presidential Fellow at the NUS Business School, during which I spent a postdoctoral stint at the Cowles Foundation at Yale University. I obtained my PhD from Princeton University after formative years at the University of Chicago and Washington University in St. Louis.
My wife, Nicole Fry, paints landscapes.
- Download my CV here.
- Email me at
kwokhao[at]nus[dot]edu[dot]sg
. - 点击阅读我的中文简历。
Upcoming Visits
2024
- Nov 26 - Dec 15: Saïd Business School, University of Oxford
- Dec 6: University College London
2025
- Apr 28 - May 2: The Wharton School, University of Pennsylvania
Upcoming Presentations
2024
- Dec 5: Imperial College London
- Dec 17/18: Winter School in Urban Economics, Université de Bourgogne
2025
- Mar 29: Kochi IO Workshop, Kochi University of Technology
- May 1: The Wharton School, University of Pennsylvania
Publications
(Click on paper descriptions to see abstracts)
Urban
transit infrastructure and inequality
(Review of Economics and Statistics, early online, Mar 2024)
- Joint work with Brandon Joel Tan.
- See also our online appendix.
- Media: The Straits
Times
(ungated)
We propose a quantitative spatial model featuring heterogeneous worker groups and their travel to consume non-tradable goods and services. We consider the opening of the Downtown Line (DTL) in Singapore, which connected regions where high-income households have residential amenities to where non-traded sectors are productive. Leveraging transit farecard data, we show that high-income workers saw large welfare gains but low-income workers gained little. Everyone enjoyed improved access to consumption opportunities, but low-income jobs in non-tradables moved to less attractive workplaces. Abstracting from consumption travel understates the disparate impact across worker groups three-fold.
Working Papers
(Click on paper descriptions to see abstracts)
Two-sided
markets shaped by platform-guided search
(R&R Econometrica)
- Joint work with Leon Musolff.
- Awarded the Rising Star Paper Prize at the 20th International Industrial
Organization Conference (2022).
- Media: California Lawyers Association, Global Competition Review
Consider firms that operate platforms matching buyers and sellers while selling goods themselves. By guiding consumers towards their own products through algorithmic recommendations, these firms could influence market outcomes - a regulatory concern. To investigate, we combine novel data about sales and recommendations on Amazon with a structural model that captures seller entry. Recommendations are highly price-elastic (-20), and many consumers (34%) only consider recommended offers. Hence, algorithmic recommendations raise the demand elasticity (from -8 to -11), intensify price competition, and increase the purchase rate. However, increased competition reduces entry (but the missing merchants are the least efficient). Focusing on self-preferencing: recommendations favor Amazon (equivalent to a 6% price discount), but this skew does not act as a barrier to entry or otherwise harm consumers. Indeed, since consumers prefer Amazon’s offers, “self-preferencing” slightly raises consumer surplus by $9 per product per month (assuming Amazon’s prices remain constant.)
Public housing at scale: Demand and welfare
- Joint work with Andrew Ferdowsian, Yiying
Tan and Luther
Yap.
- Subsumes an earlier working paper “The
dynamic allocation of public housing: Policy and spillovers”.
- Revision (with microdata) in progress.
We consider the design of a large-scale public housing program where consumers face dynamic tradeoffs over apartments rationed via lotteries and prices. We show, theoretically and empirically, that changing rules complements increasing supply. First, we present a motivating example in which supplying more housing leads households to strategically delay their applications. By waiting for “better” developments arriving tomorrow, households forgo mediocre developments available today, resulting in more vacancies. Turning to the data from the mechanism, we formulate a dynamic choice model over housing lotteries and estimate it. Under the existing mechanism, we find that increasing supply fails to lower wait times. However, when a strategyproof mechanism is implemented, vacancies and wait times fall, but prices on the secondary market rise. Under this new mechanism, building more apartments lowers wait times and reduces the upward pricing pressure on the secondary market.
Build to order: Endogenous supply in centralized mechanisms
- Joint work with Andrew Ferdowsian and
Luther Yap.
- New version (November 2024)! Submitted.
- Policy: As of Feb 2024, public housing in Singapore will be allocated
over three exercises a year instead of
four.
How should the supply of public housing be optimally designed? Although commonly used queuing mechanisms treat the supply of goods as exogenous, designers often control the inflow of goods in practice. We study a dynamic matching model where the designer minimizes a convex combination of mismatch and vacancies, motivated by the Singaporean housing allocation process, Build-To-Order. The optimal mechanism overproduces underdemanded housing relative to the proportional benchmark, and competition over housing improves match quality. Batching applications artificially generates competition and is optimal when the planner places a high weight on match quality. Following our dissemination of an early version of this paper, the Singaporean government increased batching.
Distributional effects of vehicle ownership restrictions
- Joint work with Tiffany Tsai.
- Analysis (with microdata) in progress.
- Slides available upon request.
We study vehicle population controls, their dynamic effects, alternative policy designs, and implications for efficiency and equity. We leverage data on the universe of vehicles in Singapore, the number of which is limited by the Vehicle Quota Scheme (VQS). Under the VQS, car registrations must be accompanied by permits allocated in fortnightly auctions; after ten years, car permits expire and may be renewed at the prevailing auction price. First, we observe that the effective tax on vehicle ownership fluctuates by as much as S$10,000 per year per vehicle, possibly mispricing the negative externalities of ownership and use. To explain these large fluctuations in permit prices, we formulate a dynamic equilibrium model of vehicle ownership and replacement by individuals and firms. This model will be taken to administrative microdata to evaluate welfare under the current and alternative designs.
Work in Progress
- Moving society forward: Estimating the impacts of rail connectivity on workers, firms, neighborhoods, social mobility, and tax revenue (with Siddharth George)
- Public housing at scale: Supply and equilibrium (with Shijian Yang)
Teaching
- Spring 2025: BSE3713 “Industry, Digitisation, and AI”
- Spring 2025: BSN4811 “Strategic Innovation for High Performance”
Here I also provide sample syllabi for second-year graduate classes in Empirical Industrial Organization and Urban Economics.