I am an empirical economist working at the intersection of market design, industrial organization, and public economics. My research investigates how to better design public housing systems, platform marketplaces, and transportation policy.
I am a Presidential Fellow at the Department of Strategy and Policy at the National University of Singapore (NUS) Business School, and a Visiting Fellow at the Cowles Foundation at Yale University.
In Summer 2025, I will be appointed an Assistant Professor at NUS.
I obtained my PhD from Princeton University after formative years at the University of Chicago and Washington University in St. Louis.
- Download my CV here.
- Email me at
kwokhao[at]nus[dot]edu[dot]sg
. - 查看我的中文简历。
Upcoming Visits
- Sep 1 – Dec 12: Cowles Foundation, Yale University
- Oct 22 – Oct 25: Tuck School of Business, Dartmouth College
- Nov 27: Washington University in St. Louis
Upcoming Presentations
- Oct 31: Maryland (virtual)
- Nov 15: AREUEA Virtual Seminar
- Nov 16: Brown
- Mar 9, 2024: Otaru Workshop, Hokkaido, Japan
Working Papers
(Click on paper descriptions to see abstracts)
Public housing at scale:
Dynamics, policies, and spillovers
- Joint work with Andrew Ferdowsian and
Luther Yap.
- Previously circulated as “The dynamic allocation of public housing: Policy and
spillovers”
- Revision 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.
Entry
into two-sided markets shaped by platform-guided search
- Joint work with Leon Musolff.
- Awarded the Rising Star Paper Prize at the 20th International Industrial
Organization Conference (2022)
- New version (Sep 2023)! Submitted.
We evaluate the problem of firms that operate platforms matching buyers and sellers, while also selling goods on these same platforms. By being able to guide consumer search through algorithmic recommendations, these firms can influence market outcomes, a finding that has worried regulators. To analyze this phenomenon, we combine rich novel data about sales and recommendations on Amazon Marketplace with a structural model of intermediation power. In contrast to prior literature, we explicitly model seller entry. This feature enables us to assess the most plausible theory of harm from self-preferencing, i.e. that it is a barrier to entry. We find that recommendations are highly price elastic but favor Amazon. A substantial fraction of customers only consider recommended offers, and recommendations hence noticeably raise the price elasticity of demand. By preferring Amazon’s offer, the recommendation algorithm raises consumer welfare by approximately US$4.5 billion (since consumers also prefer these offers). However, consumers are made worse off if, as a consequence, the company raises prices by more than 7.8%. Furthermore, we find no evidence of consumer harm from self-preferencing through the entry channel. Nevertheless, entry matters. The algorithm raises consumer welfare in the short and medium run by increasing the purchase rate and intensifying price competition. However, these gains are mostly offset by reduced entry in the long run.
Urban
transit infrastructure and inequality
- Joint work with Brandon Joel Tan.
- See also our online appendix.
- Revision requested by the Review of Economics and
Statistics.
How does transit expansion impact welfare and inequality? Exploiting data covering the universe of transit farecard trips from Singapore, we propose a quantitative spatial model featuring heterogeneous worker groups and travel to consume non-tradable goods and services. First, we establish that low- and high-income workers live in and travel to different places. Second, we find that low-income workers are more sensitive to changes in travel time than their high-income counterparts. Third, since low-income workers are overwhelmingly employed in non-tradable sectors, we find that changes in consumption travel induced a spatial re-organization of low-income jobs in the city. We show that the Downtown Line resulted in large welfare gains for high-income workers, but near zero for low-income workers. All workers benefited from improved access to consumption opportunities, but low-income jobs in the non-tradable sector moved to less attractive workplaces. Abstracting from consumption travel underestimates the inequality effects five-fold.
Build to order: Endogenous supply in centralized mechanisms
- Joint work with Andrew Ferdowsian and
Luther Yap.
- New version (Sep 2023)! Submitted.
How should the supply of public housing be optimally designed? Although commonly used queuing mechanisms treat the supply of goods as exogenous, designers can often control the inflow of goods in practice. We study a dynamic matching model where the designer minimizes a convex combination of mismatch count and vacancies, based on the Singaporean housing allocation process, Build-To-Order. With endogenous supply, the optimal mechanism overproduces underdemanded housing relative to the proportional benchmark, and competition over housing improves matching quality. Batching applications artificially generates competition and is optimal when the planner places a high weight on match quality.
Work in Progress
- Automobile quotas (with Tiffany Tsai)
- Product similarity and entry deterrence on two-sided markets (with Liyu Dou and Ming Li)
- City design (with Brandon Joel Tan)
Teaching
Here I provide sample syllabi for second-year graduate classes in Empirical Industrial Organization and Urban Economics.