- Quantitative Marketing
- Economics of Digitization
- Empirical Industrial Organization
- Labor Economics
Job Market Paper
- Online and Offline Retail Substitution Abstract
- Regional differences in online and offline purchasing behavior are not well understood. While pricing strategies in offline retail are tailored to their regional customers, online channels typically have homogeneous nation-wide pricing. This paper studies the regional differences in price sensitivities between online and offline markets. Combining eBay and Nielsen purchase data for two independent product categories – movies and perfumes – we create a panel dataset containing quarterly product price and quantity information at the 3-digit ZIP code level ranging from 2010 to 2015. We estimate the relationship between regional characteristics and consumers’ online and offline purchasing behavior using a nested logit demand model. Online consumers display a higher overall price sensitivity indicating that prices play a more important role here. Compared to rural areas, urban areas are more price sensitive when shopping online, but are less price sensitive when shopping offline. This suggests that urban customers are less responsive to differences in prices when shopping offline, suggesting that convenience plays a major role for these customers. In online markets, however, urban customers are more price sensitive, perhaps suggesting a higher degree of sophistication. Lastly, this paper estimates the welfare generated by the availability of the online channel for the movie as well as perfume market. The welfare gain amounts to roughly 40% of the total movie retail market and 25% of the total perfume market revenue.
- Amazon’s Price and Sales-Rank Data (with B. Mendel) Abstract
Under Review at Marketing Science
- Database Submission – This dataset contains weekly price and sales-rank information for more than 400,000 products from a broad selection of product categories on Amazon.com. The dataset ranges from 2010 to 2016 and includes, for each product, product title and product category. Additionally, most products have been successfully matched to their Universal Product Codes (UPC) and International Article Numbers (EAN) which allows researchers to link these data across different data platforms.
- Using Machine Learning to Explain Violations of the “Law of One Price” (with A. Bodoh-Creed and B. R. Hickman) Abstract
R&R at Management Science
- Substantial price variation for homogeneous goods in online markets is a well-known puzzle that has withstood attempts by empirical researchers to explain it. Economic theory suggests two possible sources of the dispersion: either market frictions are more important than previously thought, or there are subtle differences between product listings presented to e-commerce consumers that applied econometricians have failed to detect. We use a very detailed dataset consisting of posted-price listings for new Kindle Fire tablets from eBay to determine if observable listing heterogeneity can explain the price dispersion of seemingly homogeneous products. By combining a richer set of variables than previous studies with more sophisticated machine learning techniques, we can explain 42% of the dispersion. We interpret this as a bound on the influence of market frictions on price dispersion. Variables describing the amount of information in the listing are good predictors of the price, but variables describing the style of a listing’s text are good predictors as well. We identify readily interpretable groups of words that are also good predictors of price. We find a high degree of heterogeneity of the marginal effects of seller reputation and including an image in the listing, but the patterns of heterogeneity largely conform to economic intuition. A smaller, but non-trivial, latitude for market frictions remains, and we discuss their possible sources.
- How Efficient are Decentralized Auction Platforms? (with A. Bodoh-Creed and B. R. Hickman) Abstract
R&R at 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.
- The Missing Men: World War I and Female Labor Participation (with V. Gay) Abstract
Under Review at The Economic Journal
- Do sex ratio imbalances affect female labor force participation? Using spatial variation in World War I military fatalities in France, we show that the resulting scarcity of men 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 men.
Works in Progress
- 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. We 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. This data is supplemented with manually recorded demand data for selected gas stations as well as traffic data for all German highways, and is wholly unique. We 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 cell phone models in the US 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, we 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. Our 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