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. I am also a recipient of the Social Science and Humanities Research Fellowship under the Social Science Research Council of Singapore.
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 Presentations/Visits
2025
- Nov 7: NUS Applied Micro SIG
2026
- April (TBC): NUS Analytics and Operations
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).
- New version (May 2025)! Resubmitted.
- Media: California Lawyers Association, Global Competition Review
This paper investigates concerns that vertically integrated platforms like Amazon steer demand towards their own offers via algorithmic prominence, potentially harming consumers. On Amazon, for each product, the Buybox prominence algorithm selects one seller to feature, influencing which offers consumers consider. Using novel Amazon sales and Buybox (prominence) data, we estimate a structural model capturing the effects of such algorithmic prominence on consumer choices, seller pricing, and entry. We find that the platform can indeed steer demand as 95% of consumers consider only the Buybox offer. The Buybox is highly price-elastic (−21), but skews towards Amazon’s own offers, which are featured as frequently as observably similar offers priced 5% cheaper. Still, as consumers prefer these offers, this skew does not amount to self-preferencing in the sense of harming consumers: consumer surplus is roughly maximized at the estimated Amazon Buybox advantage, which balances higher prices against showing consumers their preferred offers.
Build to order: Endogenous supply in centralized mechanisms
- Joint work with Andrew Ferdowsian and
Luther Yap.
- New version (Jun 2025)! 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 a good be optimally designed, when the designer can determine the horizontal quality of the good? Although commonly used queuing mechanisms treat the supply of goods as exogenous, in practice designers often control the inflow of goods. We study a dynamic matching model where the designer minimizes a convex combination of mismatch count and unassignment. With endogenous supply, the optimal mechanism overproduces underdemanded goods relative to the proportional benchmark, and competition improves match quality. Batching applications artificially generates competition and is optimal when the planner places a high weight on match quality. We apply our results to the Singaporean housing allocation process, Build-To-Order. Following our dissemination, the Singaporean government increased batching.
Dynamic demand analysis and consumer rejections: Public
housing
- Joint work with Andrew Ferdowsian and Luther
Yap.
- Subsumes an earlier working paper “The
dynamic allocation of public housing: Policy and spillovers”.
- Revision in progress.
- Slides available upon request.
We consider the design of a large-scale public housing program in Singapore where consumers face dynamic tradeoffs over apartments rationed via lotteries and prices. We show, theoretically and empirically, that batching allocations improves welfare. First, we present a motivating example in which households strategically delay their applications in favor of “better” projects arriving in the future; batching allocations reduces wait times and unallocated apartments. Turning to microdata from the mechanism, we formulate a dynamic choice model over housing lotteries and estimate it. Welfare analysis and simulations of the planner’s problem, as well as outcomes under increased batching, are in progress.
Distributional effects of vehicle ownership restrictions
- Joint work with Tiffany Tsai.
- Analysis (with microdata) in progress.
- Slides available upon request.
Who gains and who loses when vehicle population controls are implemented? We study the distributional effects and alternative designs of the Vehicle Quota Scheme (VQS) in Singapore. Under the VQS, vehicle registrations must be accompanied by Certificates of Entitlement (COEs) allocated through fortnightly auctions; after ten years, COEs expire and may be renewed at the prevailing auction price. We first observe that COE prices vary by as much as S$10,000 per year per vehicle within the same vehicle class. While the VQS is part of a broader policy toolkit to manage congestion, we argue that its primary function today is revenue generation, with the potential for redistribution. To assess the implications of large price fluctuations, we formulate a dynamic equilibrium model of vehicle ownership and replacement and estimate it using administrative microdata. Higher COE prices between 2009 to 2014 fell most heavily on residents in the middle band of Singapore’s urban geography, relative to those in the downtown core or the outlying heartlands. Smoothing certificate supply over time could raise welfare by up to 1% in net present value by dampening price volatility. However, we find no evidence that shorter certificate durations improve welfare: more frequent renewals imply that consumers incur higher transaction costs than under the existing policy.
Work in Progress
- The effects of ride-hailing entry on transportation mode choice and vehicle ownership (with Wenxuan Xu and Sally Yang)
- Smart road pricing (with Zhihao Han, Alberto Salvo, Esther Tay, and Binglin Wang)
- 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
- (BBA) BSE3713: “Industry, Digitisation, and AI” (Spring 2025, Fall 2025)
- Media: Tech in Asia
- (BBA) BSN4811: “Strategic Innovation for High Performance” (Spring 2025, Fall 2025)
- (MSc) BMP5203: “Competitive Strategy, Digitisation, and AI” (Fall 2025)
Miscellanea
Other Work
- Humanity’s Last Exam (with Long Phan et al.)
- “Multi-modal [AI] benchmark at the frontier of human knowledge, designed to be the final closed-ended academic benchmark of its kind with broad subject coverage.”
Curios
- The Endogenous Beavers (by Grace Choo and Sally Yang)
- An econometrically-minded parody of Exploding Kittens, a card game, by two Singaporeans formerly at the LSE.
- A booster pack referencing the second half of Mastering Metrics may come some day. To my knowledge, no extension to Berry and Haile (2014, 2021, 2024) has been planned.
- Ice cream I like in Singapore: Birds of
Paradise, Island
Creamery, Wishes
- In Princeton: The Bent Spoon