- Economics of Digitization
- Empirical Industrial Organization
- Quantitative Marketing
- Labor Economics
- How Efficient are Decentralized Auction Platforms? (with A. L. Bodoh-Creed and B. R. Hickman) Abstract
Forthcoming in Review of Economic Studies
- We provide a model of a decentralized, dynamic auction market platform (e.g., eBay) in which a continuum of buyers and sellers participate in simultaneous, single-unit auctions each period. Our model accounts for the endogenous entry of agents and the impact of intertemporal optimization on bids. We estimate the structural primitives of our model using Kindle sales on eBay. We find that just over one third of Kindle auctions on eBay result in an inefficient allocation with deadweight loss amounting to 14% of total possible market surplus. We also find that partial centralization–for example, running half as many 2-unit, uniform-price auctions each day – would eliminate a large fraction of the inefficiency, but yield slightly lower seller revenues. Our results also highlight the importance of understanding platform composition effects – selection of agents into the market – in assessing the implications of market redesign. We also prove that the equilibrium of our model with a continuum of buyers and sellers is an approximate equilibrium of the analogous model with a finite number of agents.
- Using Machine Learning to Predict Price Dispersion (with A. L. Bodoh-Creed and B. R. Hickman) Abstract
- Theory suggests two sources of price dispersion amongst homogenous goods: market frictions or product heterogeneity. We collected posted-price listings for Kindle Fire tablets from eBay to determine if listing heterogeneity can explain the high degree of dispersion we observe. Using a basic set of controls and empirical techniques in line with the previous literature, we can explain only 13% of variation in posted prices, which is also in keeping with previous research. However, we can explain 42% of the dispersion by applying machine learning to a richer set of variables, which we extract from raw downloaded HTML pages. We interpret this number as a bound on the role of market frictions in driving price dispersion. Variables describing the amount of information in the listings, the style of the listings, and the content of the listings' text are effective price predictors independently of one another. Our analysis suggests that the content of the listings' text plays a primal role in generating the predictions of the machine learning estimator. We repeat our analysis on a cross-section of products across a variety of categories on eBay, including household products, sporting goods, and other consumer electronics, and we find a comparable degree of price predictability across all of the products.
- The Missing Men: World War I and Female Labor Participation (with V. Gay) Abstract
- Using spatial variation in World War I military fatalities in France, we show that the scarcity of men due to the war generated an upward shift in female labor force participation that persisted throughout the interwar period. Increased female labor supply accounts for this result: deteriorated marriage market conditions for single women and negative income shocks to war widows induced many of these women to enter the labor force after the war. In contrast, firms did not increase their demand for female labor to compensate for the scarcity of male labor.
Works in Progress
- Main Street versus Cyberspace: Consumers' Substitution Between Online and Offline Retail Abstract
- While online sales accounted for half of retail sales growth in 2017, they still make up only 10% of total retail sales in the United States. This stands in contrast to initial predictions that suggested that consumers would migrate online and turn away from traditional retail. Using a unique dataset covering both online and offline purchases, I estimate a flexible demand system where consumers have the option to purchase goods online and offline to explore the factors driving the transitions (or lack thereof) to online retailers. I match product-level data from AC Nielsen and eBay with consumer and product characteristics to create a dataset containing millions of transactions at the 3-digit ZIP code level. I find that customers in the electronic market are two to four times more price sensitive than customers in traditional markets, which makes sense given the low cost of price searches online. I also find that urban shoppers are more price sensitive than rural shoppers when shopping online, but the reverse holds when shopping offline. One potential explanation is that urban consumers are more experienced comparing prices online, while convenience might be more important for urban consumers when shopping offline. I then use the estimated price elasticities for each market to predict the total welfare gained from the availability of electronic retail, and I find a welfare gain of roughly 25%-40% of total market revenue.
- Pricing Strategies, Competition, and Consumer Welfare: Evidence from the German and Austrian Retail Gasoline Market Abstract
- This paper uses spatial and temporal fluctuations in retail gasoline prices to study the effect of competition on pricing behavior and how government-mandated price restrictions impact consumers. I use hourly price data for more than 16,500 gas stations in Austria and Germany (more than 90% of the market), collected since April 2012. These data are supplemented with manually recorded demand data for selected gas stations as well as traffic data for all German highways, and is wholly unique. I analyze nation-wide price fluctuations, cross-network price patterns, and price competition between adjacent gas stations that directly compete for motorists. Price elasticity estimates for different consumer groups show that the pricing behavior observed in the Austrian and German market cannot be explained as pure demand shocks. The data suggest that gas stations temporally price discriminate: in Germany, gas stations set high prices for price-inelastic business / morning consumers and low prices for the highly elastic leisure / evening consumers. In Austria, governmental regulation prevents gas stations from replicating the patterns in Germany, leading to unintended consequences: consumers face a less volatile price with higher daily minima in Austria, forcing price-sensitive consumers to refill at higher average prices.
- Quantifying the Welfare Effects in Network Markets (with J. D. Donna, D. Masterov, and G. Veramendi) Abstract
- We empirically investigate the welfare implications of a reduction in the level of frictions and price dispersion in online retail markets. Our identification strategy exploits the unique circumstance that, in the online trading platform eBay, we have access to “click-stream” data that records which listings appear in buyers’ searches, which listings buyers click on, and which listings they bid for, even if they do not end up buying that product. Click-stream data provides the information needed to reconstruct the links (which buyers interact with which sellers) in the network. We perform the welfare analysis using a three-step framework. First, we reconstruct the realized network of buyers and sellers using click-stream data. Second, we develop a tractable empirical networks’ model, and estimate its the primitives (i.e. distribution of buyers’ valuations) that characterize the model’s underlying demand preferences conditional on the realized network. Third, we use the estimated demand preferences and network structure to perform a counterfactual analysis. In the counterfactual analysis we compare the actual outcome (i.e. welfare under the actual level of frictions in eBay) to a counterfactual outcome, whereby we will use the estimated demand preferences and the behavioral buyer-seller model to compute the welfare under an alternative policy that would reduce the level of frictions and price dispersion in eBay.
- Innovation in the Market for Cell Phones in USA and China (with M. Cheng and R. B. Freeman) Abstract
- Cell phones are an archetypal product of the 21st century knowledge economy. This paper develops a new dataset on the prices and attributes of close-to-all cell phone models in the U.S. and China and uses the data to estimate hedonic price equations that help assess the rate and diffusion of technological change in the industry. The equations show broadly similar rates of technological improvements and diffusion of improvements in the two countries, despite differences in GDP / capita and in economic institutions. The rapid technological change combined with the 2-3 hours per day that consumers use the phones suggests that standard measures of GDP understate the contribution of cell phones to economic well-being.
- Recovery from Bidding Fever: Why pay more than 102% to buy a Gift Card? Abstract
- On eBay, gift certificates often sell for more than their face values. About 51.6% of Amazon gift certificates sold on eBay, for example, sell for prices that are ‘too high’ – on average 104.1% of face value. People often attribute this apparent overpayment to bidding fever or pseudo-endowment effects. However, using a novel dataset of eBay transactions, I show that about half of all Amazon gift card overpayment occurs in fact in Buy-it-now sales, and thus does not involve bidding, much less bidding fever. My data reveals that overpayment is not random; rather, it is highly cyclic. In fact, overpayments appear to be rationalized by institutional features such as eBay reward programs and special offers. These features affect bidding and buying behavior in meaningful ways and should thus be taken into consideration in future research using eBay data.
- Design and Implementation of a Privacy Preserving Electronic Health Record Linkage Tool in Chicago (with A. N. Kho et al. J. P. Cashy, K. L. Jackson, A. R. Pah, S. Goel, J. E. Humphries, S. D. Kominers, B. N. Hota, S. A. Sims, B. A. Malin, D. D. French, T. L. Walunas, D. Meltzer, E. Kaleba, R. Jones, and W. L. Galanter) Abstract
Journal of the American Medical Informatics Association, 2015
- The Chicago HealthLNK is a shared data resource for researchers and public health officials that deidentifies and links patient data across seven institutions within the city of Chicago. We developed a computer application to perform standardized data cleaning, pre-processing, and hashing of patient identifiers to remove all protected health information using the HIPAA compliant SHA-512 algorithm. Our matching algorithm generated a 92-99% match rate compared with an operational master patient index. Currently the Chicago Health Atlas includes clinical data (diagnoses, medications, laboratory tests, and vital signs) on over 5.6 million records in the Chicago region, and over 1.2 million patients within the city of Chicago (606xx zip codes) for the years 2006 to 2012. A limited set of aggregated clinical data on chronic conditions are made publicly available through a Health Atlas community website.
- The Costratified Hilbert Space Structure of an SU(3) Lattice Gauge Model Abstract
- The weak and strong interactions are modelled by non-abelian gauge field theory. Perturbation methods are the usual approach in dealing with the corresponding gauge fields. For some fundamental phenomena of gauge theory, however, only non-perturbative methods are applicable. In this work, we analyse a toy model of classical SU(3) lattice gauge theory on a single plaquette.
At first, we give an introduction of the mathematical foundations and the model is analysed. In order to reduce the gauge symmetry, we subsequently apply the singular Marsden-Weinstein reduction to the phase space of our system, a Hamiltonian G-manifold. This procedure yields the reduced phase space, a symplectic stratified space.
The reduced phase space is a singular object which is composed of seven different connected components: three zero-dimensional strata, three two-dimensional strata and one four-dimensional stratum. The physical Hilbert space of our system arises by geometric quantisation. We characterise and analyse the Hilbert spaces associated with the singular strata of the SU(3) toy model. The set of these single Hilbert spaces amounts to the structure of a costratified Hilbert space. The results obtained may be regarded as a contribution to non-perturbative quantisation procedures in lattice gauge theory.
- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2017
- New Tools for Acquisition / Analysis of Internet Data (PhD), Harvard University, NBER, 2016
- Practical Computing for Economists (PhD), University of Chicago, 2015
- Introduction to Data Acquisition and Data Management for Economic Research (PhD), UCLA Anderson, 2014
- Introduction to Computational Methods in Economics (PhD), University of Chicago, 2014
- Principles of Microeconomics, Economic Analysis 1 (BA), University of Chicago, 2013
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- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2016
- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2015
- Practical Computing for Economists (PhD), University of Chicago, 2014
- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2014
- Introduction to Computational Methods in Economics (PhD), University of Chicago, 2013
- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2013
- Principles of Microeconomics, Economic Analysis 1 (BA), University of Chicago, 2012
- Economic Research Experience for Undergraduates (BA), Becker Friedman Institute, University of Chicago, 2012
- Microeconomics (Gibbs; Executive MBA), Booth School of Business in Chicago, London, and Hong Kong, 2015
- Big Data (Taddy; PhD), Booth School of Business, 2015
- Microeconomics (Stole; Executive MBA), Booth School of Business in Chicago, London, and Hong Kong, 2014
- Microeconomics (Gibbs; Executive MBA), Booth School of Business in Chicago, London, and Singapore, 2013
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- Evolutionary Game Theory (Szentes; PhD), University of Chicago, 2014
- Introduction to Theory-Based Empirical Methods (Hickman; PhD), University of Chicago, 2014
- Microeconomics (Gibbs; Executive MBA), Booth School of Business in Chicago, London, and Hong Kong, 2014
- Topics in Matching and Market Design (Kominers; PhD), University of Chicago, 2013
- Evolutionary Game Theory (Szentes; PhD), University of Chicago, 2013
- Introduction to Theory-Based Empirical Methods (Hickman; PhD), University of Chicago, 2013
- Principles of Microeconomics, Economic Analysis 1 - Honors (Lima; BA), University of Chicago, 2012
- Principles of Macroeconomics, Economic Analysis 4 (Santamaria; BA), University of Chicago, 2011
- Quantum Mechanics I and II (Rudolph; DiplPhys), University of Leipzig, 2007-2008
- Calculus I (Freistühler; DiplMath), University of Leipzig, 2004-2005