Scott D. Kominers

Lecturer of Business Administration

My actual homepage is http://www.scottkom.com/

I am a Junior Fellow at the Harvard Society of Fellows, an Affiliate of theHarvard Center of Mathematical Sciences and Applications, an Associate of the Harvard Center for Research on Computation and Society, a Research Scientist at the Harvard Program for Evolutionary Dynamics, and a Research Economist at the National Bureau of Economic Research. In Spring 2016, I will also be a Visiting Fellow at the Oxford Martin School. From 2011-2013, I was the inaugural Research Scholar at the Becker Friedman Institute for Research in Economics at the University of Chicago.

I completed my PhD in Business Economics at Harvard University in Spring 2011, with the dissertation "Matching Models of Markets." Before that, I graduated from Harvard summa cum laude and Phi Beta Kappa inMathematics (with a minor in Ethnomusicology) in Spring 2009, and completed my Masters of Arts at Harvard in Spring 2010.

I am co-leader of the Human Capital and Economic Opportunity "Inequality: Measurement, Interpretation, and Policy" working group (MIP).

Book Chapters

  1. Empirical Evidence on the Behavior and Impact of Patent Trolls: A Survey

    Lauren Cohen, Umit Gurun and Scott Duke Kominers

    We survey the empirical literature on non-practicing entity (NPE) litigation behavior and its consequences. We document both aggregate trends and cross-sectional differences amongst various types of NPEs. Survey evidence illustrates a number of ways in which NPEs can potentially act opportunistically, and indicates at least some instances and consequences of observed NPE opportunism. Large-sample empirical work has recently begun corroborating and amplifying the findings from survey evidence. NPEs on average behave as "patent trolls." Indeed, NPEs hold and frequently litigate patents that are likely to be at least partially invalidated; moreover, NPEs target cash irrespective of its relation to alleged infringement. Cash-targeting is neither the main driver of practicing entity (PE) intellectual property (IP) litigation, nor of non-IP litigation against publicly traded firms. The empirical evidence suggests, however, that not all NPEs exhibit trolling behavior — the cash-targeting observed in the data is primarily the behavior of large patent aggregators, rather than small inventors. NPE patent trolling has a real negative impact on targeted firms, without any increase in innovation, technology transfer, or other counterbalancing benefits measured thus far.

    Keywords: Patent trolls; NPEs; PAEs; innovation; patents; Patents; Lawsuits and Litigation; Innovation and Invention;

    Citation:

    Cohen, Lauren, Umit Gurun, and Scott Duke Kominers. "Empirical Evidence on the Behavior and Impact of Patent Trolls: A Survey." In Patent Assertion Entities and Competition Policy, edited by D. Daniel Sokol. Cambridge University Press, forthcoming. View Details

Working Papers

  1. Configurations of Extremal Type II Codes

    Noam D. Elkies and Scott Duke Kominers

    We prove configuration results for extremal Type II codes, analogous to the configuration results of Ozeki and of the second author for extremal Type II lattices. Specifically, we show that for n∈{8,24,32,48,56,72,96} every extremal Type II code of length n is generated by its codewords of minimal weight. Where Ozeki and Kominers used spherical harmonics and weighted theta functions, we use discrete harmonic polynomials and harmonic weight enumerators. Along the way we introduce "t12-designs" as a discrete analog of Venkov's spherical designs of the same name.

    Keywords: Mathematical Methods;

    Citation:

    Elkies, Noam D., and Scott Duke Kominers. "Configurations of Extremal Type II Codes." Working Paper, March 2015. View Details
  2. Do People Shape Cities, or Do Cities Shape People? The Co-evolution of Physical, Social, and Economic Change in Five Major U.S. Cities

    Nikhil Naik, Scott Duke Kominers, Ramesh Raskar, Edward L. Glaeser and Cesar Hidalgo

    Urban change involves transformations in the physical appearance and the social composition of neighborhoods. Yet, the relationship between the physical and social components of urban change is not well understood due to the lack of comprehensive measures of neighborhood appearance. Here, we introduce a computer vision method to quantify change in physical appearance of streetscapes and generate a dataset of physical change for five large American cities. We combine this dataset with socioeconomic indicators to explore whether demographic and economic changes precede, follow, or co-occur with changes in physical appearance. We find that the strongest predictors of improvement in a neighborhood’s physical appearance are population density and share of college-educated adults. Other socioeconomic characteristics, like median income, share of vacant homes, and monthly rent, do not predict improvement in physical appearance. We also find that neighborhood appearances converge to the initial appearances of bordering areas, supporting the Burgess “invasion” theory. In addition, physical appearance is more likely to improve in neighborhoods proximal to the central business district. Finally, we find modest support for “tipping” and “filtering” theories of urban change.

    Keywords: Demographics; Urban Development; Change; Economics;

    Citation:

    Naik, Nikhil, Scott Duke Kominers, Ramesh Raskar, Edward L. Glaeser, and Cesar Hidalgo. "Do People Shape Cities, or Do Cities Shape People? The Co-evolution of Physical, Social, and Economic Change in Five Major U.S. Cities." Working Paper. View Details
  3. A Theory of Intergenerational Mobility

    Gary Becker, Scott Duke Kominers, Kevin Murphy and Jorg L. Spenkuch

    We develop a model of intergenerational resource transmission that emphasizes the link between cross-sectional inequality and intergenerational mobility. By drawing on first principles of human capital theory, we derive several novel results. In particular, we show that, even in a world with perfect capital markets and without differences in innate ability, wealthy parents invest, on average, more in their offspring than poorer ones. As a result, persistence of economic status is higher at the top of the income distribution than in the middle. Successive generations of the same family may even cease to regress towards the mean. Moreover, we demonstrate that government interventions intended to ameliorate inequality may in fact lower intergenerational mobility—even when they do not directly favor the rich. Lastly, we consider how mobility is affected by changes in the marketplace.

    Keywords: intergenerational mobility; inequality; human capital; complementarities; Human Capital; Equality and Inequality; Income; Family and Family Relationships;

    Citation:

    Becker, Gary, Scott Duke Kominers, Kevin Murphy, and Jorg L. Spenkuch. "A Theory of Intergenerational Mobility." Working Paper, August 2015. View Details
  4. Paying (for) Attention: The Impact of Information Processing Costs on Bayesian Inference

    Scott Duke Kominers, Xiaosheng Mu and Alexander Peysakhovich

    Human information processing is often modeled as costless Bayesian inference. However, research in psychology shows that attention is a computationally costly and potentially limited resource. We study a Bayesian individual for whom computing posterior beliefs is costly. Such an agent faces a tradeoff between economizing on attention costs and having more accurate beliefs. We show that even small processing costs can lead to significant departures from the standard costless processing model. There exist situations where beliefs can cycle persistently and never converge. In addition, when updating is costly, agents are more sensitive to signals about rare events than to signals about common events. Thus, these individuals can permanently overestimate the likelihood of rare events (e.g., the probability of a plane crash). There is a commonly held assumption in economics that individuals will converge to correct beliefs/optimal behavior given sufficient experience. Our results contribute to a growing literature in psychology, neuroscience, and behavioral economics suggesting that this assumption is both theoretically and empirically fragile.

    Keywords: Behavior; Cognition and Thinking; Economics;

    Citation:

    Kominers, Scott Duke, Xiaosheng Mu, and Alexander Peysakhovich. "Paying (for) Attention: The Impact of Information Processing Costs on Bayesian Inference." Working Paper, February 2016. View Details
  5. Full Substitutability

    John William Hatfield, Scott Duke Kominers, Alexandru Nichifor, Michael Ostrovsky and Alexander Westkamp

    Various forms of substitutability are essential for establishing the existence of equilibria and other useful properties in diverse settings such as matching, auctions, and exchange economies with indivisible goods. We extend earlier models' canonical definitions of substitutability to settings in which an agent can be both a buyer in some transactions and a seller in others, and show that all these definitions are equivalent. We introduce a new class of substitutable preferences that allows us to model intermediaries with production capacity. We then prove that substitutability is preserved under economically important transformations such as trade endowments, mergers, and limited liability. We also show that substitutability corresponds to submodularity of the indirect utility function, the single improvement property, and a no complementarities condition. Finally, we show that substitutability implies the monotonicity conditions known as the Laws of Aggregate Supply and Demand.

    Keywords: Market Design; Balance and Stability;

    Citation:

    Hatfield, John William, Scott Duke Kominers, Alexandru Nichifor, Michael Ostrovsky, and Alexander Westkamp. "Full Substitutability." Working Paper, May 2015. View Details
  6. Chain Stability in Trading Networks

    John William Hatfield, Scott Duke Kominers, Alexandru Nichifor, Michael Ostrovsky and Alexander Westkamp

    We show that in general trading networks with bilateral contracts, a suitably adapted chain stability concept (Ostrovsky, 2008) is equivalent to stability (Hatfield and Kominers, 2012; Hatfield et al., 2013) if all agents' preferences are fully substitutable and satisfy the Laws of Aggregate Supply and Demand. Furthermore, in the special case of trading networks with transferable utility, an outcome is consistent with competitive equilibrium if and only if it is not blocked by any chain of contracts.

    Keywords: Contracts; Market Design; Balance and Stability;

    Citation:

    Hatfield, John William, Scott Duke Kominers, Alexandru Nichifor, Michael Ostrovsky, and Alexander Westkamp. "Chain Stability in Trading Networks." Working Paper, April 2015. View Details
  7. Costly Concessions: An Empirical Framework for Matching with Imperfectly Transferable Utility

    Alfred Galichon, Scott Duke Kominers and Simon Weber

    We introduce an empirical framework for models of matching with imperfectly transferable utility and unobserved heterogeneity in tastes. Our framework allows us to characterize matching equilibrium in a flexible way that includes as special cases the classic fully- and non-transferable utility models, collective models, and settings with taxes on transfers, deadweight losses, and risk aversion. We allow for the introduction of a very general class of unobserved heterogeneity on agents' preferences. Under minimal assumptions, we show existence and uniqueness of equilibrium. We provide two algorithms to compute the equilibria in our model. The first algorithm operates under any structure of heterogeneity in preferences. The second algorithm is more efficient, but applies only in the case when random utilities are logit. We show that the log-likelihood of the model has a particularly simple expression and we compute its derivatives. As an application, we build a model of marriage with two-sided preferences over the partner type and private consumption. We estimate our model using the 2013 "Living Costs and Food Survey" database.

    Keywords: sorting; matching; Marriage Market; intrahousehold allocation; Imperfectly Transferable Utility; Marketplace Matching; Game Theory;

    Citation:

    Galichon, Alfred, Scott Duke Kominers, and Simon Weber. "Costly Concessions: An Empirical Framework for Matching with Imperfectly Transferable Utility." Working Paper, January 2016. View Details
  8. Stability, Strategy-Proofness, and Cumulative Offer Mechanisms

    John William Hatfield, Scott Duke Kominers and Alexander Westkamp

    We consider the setting of many-to-one matching with contracts, where firms may demand multiple contracts but each worker desires at most one contract. We introduce three novel conditions—observable substitutability, observable size monotonicity, and non-manipulatability—and show that when these conditions are satisfied, the cumulative offer mechanism is the unique mechanism that is stable and strategy-proof (for workers). Moreover, when the choice function of some firm fails any of our three conditions, one can construct unit-demand choice functions for the other firms such that no stable and strategy-proof mechanism exists. In the final part of the paper, we characterize the class of choice functions for which the cumulative offer mechanism is guaranteed to yield a stable outcome.

    Keywords: Matching with Contracts; stability; Strategy-proofness; Substitutability; Size monotonicity; Cumulative offer mechanism; Contracts; Market Design; Marketplace Matching; Balance and Stability;

    Citation:

    Hatfield, John William, Scott Duke Kominers, and Alexander Westkamp. "Stability, Strategy-Proofness, and Cumulative Offer Mechanisms." Working Paper, July 2015. View Details
  9. Hidden Substitutes

    John William Hatfield and Scott Duke Kominers

    In this paper, we show that preferences exhibiting some forms of complementarity in fact have an underlying substitutable structure. Specifically, we show that some preferences that are not substitutable in the setting of many-to-one matching with contracts become substitutable when an employer is allowed to sign multiple contracts with an individual worker. These substitutably completable preferences guarantee the existence of stable outcomes, even though stable outcomes are not guaranteed, in general, when complementarities are present. Our results imply the existence of a stable, strategy-proof mechanism for allocating workers with specialized skillsets; moreover, our results give new insight into the existing applications of matching with contracts to cadet–branch matching and the design of affirmative action programs.

    Keywords: Many-to-One Matching; Many-to-Many Matching; stability; Substitutes; Matching with Contracts; Slot-Specific Priorities; Sherlock; Market Design; Contracts; Marketplace Matching; Balance and Stability;

    Citation:

    Hatfield, John William, and Scott Duke Kominers. "Hidden Substitutes." Working Paper, September 2014. View Details
  10. Strategy-Proofness, Investment Efficiency, and Marginal Returns: An Equivalence

    John William Hatfield, Fuhito Kojima and Scott Duke Kominers

    We show that a mechanism induces an agent to make efficient ex ante investment choices if and only if it rewards that agent with his marginal surplus; additionally, for an ex post efficient mechanism, these properties are equivalent to strategy-proofness for the agent. Our results extend to settings with uncertainty; moreover, they have analogs for mechanisms that are only approximately efficient and approximately incentive compatible. Among other applications, our results imply both that under the worker-optimal stable mechanism, workers are incentivized to make efficient human capital investments before entering the labor market, and that second-price auctions induce efficient bidder participation.

    Keywords: Strategy-proofness; Investment efficiency; Providing marginal rewards; Vickrey-Clarke-Groves mechanisms; Mechanism design; Market Design; Human Capital;

    Citation:

    Hatfield, John William, Fuhito Kojima, and Scott Duke Kominers. "Strategy-Proofness, Investment Efficiency, and Marginal Returns: An Equivalence." Working Paper, January 2015. View Details
  11. Shielded Innovation

    Lauren Cohen, Umit Gurun and Scott Duke Kominers

    We show that increased litigation risk has driven innovators to shield themselves by shifting innovation out of industry and into universities. We show both theoretically and empirically that litigation by Non-Practicing Entities (NPEs) pushes innovation to spaces with reduced litigation threat. Innovation has shifted into universities (and away from public and private firms) in exactly those industries with the most aggressive NPE litigation, precisely following extensive NPE litigation. The extent of innovation shielding is large and significant. An increase of 100 NPE lawsuits in an industry shifts up the university share of innovation by roughly 70% in subsequent years (t=5.34).

    Keywords: Patent trolls; patents; NPEs; PAEs; innovation; Patents;

    Citation:

    Cohen, Lauren, Umit Gurun, and Scott Duke Kominers. "Shielded Innovation." Working Paper, June 2015. View Details
  12. Patent Trolls: Evidence from Targeted Firms

    Lauren Cohen, Umit G. Gurun and Scott Duke Kominers

    We develop a theoretical model of, and provide the first large-sample evidence on, the behavior and impact of non-practicing entities (NPEs) in the intellectual property space. Our model shows that NPE litigation can reduce infringement and support small inventors. However, the model also shows that as NPEs become effective at bringing frivolous lawsuits, the resulting defense costs inefficiently crowd out some firms that, absent NPEs, would produce welfare-enhancing innovations without engaging in infringement. Our empirical analysis shows that on average, NPEs appear to behave as opportunistic patent trolls. NPEs sue cash-rich firms—a one standard deviation increase in cash holdings roughly doubles a firm's chance of being targeted by NPE litigation. We find moreover that NPEs target cash unrelated to the alleged infringement at essentially the same frequency as they target cash related to the alleged infringement. By contrast, cash is neither a key driver of intellectual property lawsuits by practicing entities (e.g., IBM and Intel), nor of any other type of litigation against firms. We find further suggestive evidence of NPE opportunism, such as forum shopping and targeting of firms that may have reduced ability to defend themselves against litigation. We find that NPE litigation has a real negative impact on innovation at targeted firms: firms substantially reduce their innovative activity after settling with NPEs (or losing to them in court). Moreover, we neither find any markers of significant NPE pass-through to end innovators, nor of a positive impact of NPEs on innovation in the industries in which they are most prevalent.

    Keywords: Patent trolls; NPEs; innovation; patents; Patents; Ethics; Lawsuits and Litigation; Innovation and Invention; Corporate Finance;

    Citation:

    Cohen, Lauren, Umit G. Gurun, and Scott Duke Kominers. "Patent Trolls: Evidence from Targeted Firms." Harvard Business School Working Paper, No. 15-002, July 2014. (Revised April 2016.) View Details

Business Writing

Other Publications and Materials

Economic Research

  1. Holdout in the Assembly of Complements: A Problem for Market Design

    Scott Duke Kominers and E. Glen Weyl

    Holdout problems prevent private (voluntary and self-financing) assembly of complementary goods—such as land or dispersed spectrum—from many self-interested sellers. While mechanisms that fully respect sellers' property rights cannot alleviate these holdout problems, traditional solutions, such as the use of coercive government powers of "eminent domain" to expropriate property, can encourage wasteful and unfair assemblies. We discuss the problems holdout creates for the efficient operation of markets and how previous approaches have used regulated coercion to address these challenges. We then investigate when encouraging competition can partially or fully substitute for coercion, focusing particularly on questions of spectrum allocation.

    Citation:

    Kominers, Scott Duke, and E. Glen Weyl. "Holdout in the Assembly of Complements: A Problem for Market Design." American Economic Review: Papers and Proceedings 102, no. 3 (May 2012): 360–365. View Details
  2. Vacancies in Supply Chain Networks

    John William Hatfield and Scott Duke Kominers

    We use the supply chain matching framework to study the effects of firm exit. We show that the exit of an initial supplier or end consumer has monotonic effects on the welfare of initial suppliers and end consumers but may simultaneously have positive and negative effects on intermediaries. Furthermore, we demonstrate that there are no clear comparative statics for the effects of intermediary exit on the welfare of other firms; most surprisingly, intermediary exit may diminish the welfare of other firms at the same level of the supply chain.

    Keywords: matching; networks; stability; Vacancy chains;

    Citation:

    Hatfield, John William, and Scott Duke Kominers. "Vacancies in Supply Chain Networks." Economic Letters 119, no. 3 (June, 2013): 354–357. View Details
  3. On Derivatives Markets and Social Welfare: A Theory of Empty Voting and Hidden Ownership

    Jordan M. Barry, John William Hatfield and Scott Duke Kominers

    In the past twenty-five years, derivatives markets have grown exponentially. Large, modern derivatives markets increasingly enable in- vestors to hold economic interests in corporations without owning voting rights, and vice versa. This leads to both empty voters—investors whose voting rights in a corporation exceed their economic interests— and hidden owners—investors whose economic interests exceed their voting rights. We present formal analysis that shows how, when financial markets are opaque, empty voting and hidden ownership can render financial markets unpredictable, unstable, and inefficient. By contrast, we show that when financial markets are transparent, empty voting and hidden ownership have dramatically different effects: they follow predictable patterns, encourage stable outcomes, and promote efficiency. Our analysis lends insight into the operation of securities markets in general and derivatives markets in particular. It also provides a new justification for a robust mandatory disclosure regime and facilitates analysis of proposed substantive securities regulations.

    Citation:

    Barry, Jordan M., John William Hatfield, and Scott Duke Kominers. "On Derivatives Markets and Social Welfare: A Theory of Empty Voting and Hidden Ownership." Virginia Law Review 99, no. 6 (2013): 1103–1168. View Details
  4. Crowdsourcing City Government: Using Tournaments to Improve Inspection Accuracy

    Edward Glaeser, Andrew Hillis, Scott Duke Kominers and Michael Luca

    The proliferation of big data makes it possible to better target city services like hygiene inspections, but city governments rarely have the in-house talent needed for developing prediction algorithms. Cities could hire consultants, but a cheaper alternative is to crowdsource competence by making data public and offering a reward for the best algorithm. A simple model suggests that open tournaments dominate consulting contracts when cities can tolerate risk and when there is enough labor with low opportunity costs. We also report on an inexpensive Boston-based restaurant tournament, which yielded algorithms that proved reasonably accurate when tested "out-of-sample" on hygiene inspections.

    Keywords: user-generated content; operations; tournaments; policy-making; Machine learning; online platforms; Data and Data Sets; Mathematical Methods; City; Infrastructure; Business Processes; Government and Politics;

    Citation:

    Glaeser, Edward, Andrew Hillis, Scott Duke Kominers, and Michael Luca. "Crowdsourcing City Government: Using Tournaments to Improve Inspection Accuracy." American Economic Review: Papers and Proceedings 106, no. 5 (May 2016): 114–118. View Details
  5. Convergence of Position Auctions under Myopic Best-Response Dynamics

    Matthew Cary, Aparna Das, Benjamin Edelman, Ioannis Giotis, Kurtis Heimerl, Anna Karlin, Scott Duke Kominers, Claire Mathieu and Michael Schwarz

    We study the dynamics of multi-round position auctions, considering both the case of exogenous click-through rates and the case in which click-through rates are determined by an endogenous consumer search process. In both contexts, we demonstrate that the dynamic auctions converge to their associated static, envy-free equilibria. Furthermore, convergence is efficient, and the entry of low-quality advertisers does not slow convergence. Because our approach predominantly relies on assumptions common in the sponsored search literature, our results suggest that dynamic position auctions converge more generally.

    Keywords: sponsored search; advertising; google; equilibrium selection; Online Advertising; Advertising Industry;

    Citation:

    Cary, Matthew, Aparna Das, Benjamin Edelman, Ioannis Giotis, Kurtis Heimerl, Anna Karlin, Scott Duke Kominers, Claire Mathieu, and Michael Schwarz. "Convergence of Position Auctions under Myopic Best-Response Dynamics." ACM Transactions on Economics and Computation 2, no. 3 (July 2014): 1–20. View Details
  6. To Groupon or Not to Groupon: The Profitability of Deep Discounts

    Benjamin Edelman, Sonia Jaffe and Scott Duke Kominers

    We examine the profitability and implications of online discount vouchers, a relatively new marketing tool that offers consumers large discounts when they prepay for participating firms' goods and services. Within a model of repeat experience good purchase, we examine two mechanisms by which a discount voucher service can benefit affiliated firms: price discrimination and advertising. For vouchers to provide successful price discrimination, the valuations of consumers who have access to vouchers must generally be lower than those of consumers who do not have access to vouchers. Offering vouchers tends to be more profitable for firms which are patient or relatively unknown, and for firms with low marginal costs. Extensions to our model accommodate the possibilities of multiple voucher purchases and firm price re-optimization. Despite the potential benefits of online discount vouchers to certain firms in certain circumstances, our analysis reveals the narrow conditions in which vouchers are likely to increase firm profits.

    Keywords: voucher discounts; Groupon; experience goods; repeat purchase; Online Technology; Marketing Strategy; Marketing Communications;

    Citation:

    Edelman, Benjamin, Sonia Jaffe, and Scott Duke Kominers. "To Groupon or Not to Groupon: The Profitability of Deep Discounts." Marketing Letters 27, no. 1 (March 2016): 39–53. (First circulated in June 2011. Featured in Working Knowledge: Is Groupon Good for Retailers? Excerpted in HBR Blogs: To Groupon or Not To Groupon: New Research on Voucher Profitability.) View Details
  7. Agglomerative Forces and Cluster Shapes

    William R. Kerr and Scott Duke Kominers

    We model spatial clusters of similar firms. Our model highlights how agglomerative forces lead to localized, individual connections among firms, while interaction costs generate a defined distance over which attraction forces operate. Overlapping firm interactions yield agglomeration clusters that are much larger than the underlying agglomerative forces themselves. Empirically, we demonstrate that our model's assumptions are present in the structure of technology and labor flows within Silicon Valley. Our model further identifies how the lengths over which agglomerative forces operate influence the shapes and sizes of industrial clusters; we confirm these predictions using variations across patent technology clusters.

    Keywords: agglomeration; clusters; networks; industrial organization; Silicon Valley; entrepreneurship; Technology Flows; patents; Networks; Technology; Industry Clusters; Entrepreneurship; California;

    Citation:

    Kerr, William R., and Scott Duke Kominers. "Agglomerative Forces and Cluster Shapes." Review of Economics and Statistics 97, no. 4 (October 2015): 877–899. View Details
  8. Contract Design and Stability in Many-to-Many Matching

    John William Hatfield and Scott Duke Kominers

    We develop a model of many-to-many matching with contracts that subsumes as special cases many-to-many matching markets and buyer/seller markets with heterogeneous and indivisible goods. In our setting, substitutable preferences are sufficient to guarantee the existence of stable outcomes; moreover, in contrast to results for the setting of many-to-one matching with contracts, if any agent’s preferences are not substitutable, then the existence of a stable outcome cannot be guaranteed. In many-to-many matching with contracts, a new market design issue arises: the design of the contract language can impact the set of stable outcomes. Bundling contractual primitives encourages substitutability of agents’ preferences over contracts and makes stable outcomes more likely to exist; however, bundling also makes the contractual language less expressive. Consequently, we see that, in choosing contract language, market designers face a tradeoff between expressiveness and stability.

    Keywords: Many-to-Many Matching; stability; Substitutes; Contract Design; Contracts; Marketplace Matching; Balance and Stability;

    Citation:

    Hatfield, John William, and Scott Duke Kominers. "Contract Design and Stability in Many-to-Many Matching." Games and Economic Behavior (forthcoming). View Details
  9. Matching with Slot-Specific Priorities: Theory

    Scott Duke Kominers and Tayfun Sonmez

    We introduce a two-sided, many-to-one matching with contracts model in which agents with unit demand match to branches that may have multiple slots available to accept contracts. Each slot has its own linear priority order over contracts; a branch chooses contracts by filling its slots sequentially, according to an order of precedence. We demonstrate that in these matching markets with slot-specific priorities, branches’ choice functions may not satisfy the substitutability conditions typically crucial for matching with contracts. Despite this complication, we are able to show that stable outcomes exist in the slot-specific priorities framework and can be found by a cumulative offer mechanism that is strategy proof and respects unambiguous improvements in priority.

    Keywords: market design; Matching with Contracts; stability; Strategy-proofness; School Choice; Affirmative Action; Airline Seat Upgrades; Contracts; Market Design; Marketplace Matching; Balance and Stability;

    Citation:

    Kominers, Scott Duke, and Tayfun Sonmez. "Matching with Slot-Specific Priorities: Theory." Theoretical Economics (forthcoming). View Details
  10. Design and Implementation of a Privacy Preserving Electronic Health Record Linkage Tool in Chicago

    Abel Kho, John Cashy, Kathryn Jackson, Adam Pah, Satyender Goel, Jorn Boehnke, John Eric Humphries, Scott Duke Kominers and et al.

    Objective
    To design and implement a tool that creates a secure, privacy preserving linkage of electronic health record (EHR) data across multiple sites in a large metropolitan area in the United States (Chicago, IL), for use in clinical research.
    Methods
    The authors developed and distributed a software application that performs standardized data cleaning, preprocessing, and hashing of patient identifiers to remove all protected health information. The application creates seeded hash code combinations of patient identifiers using a Health Insurance Portability and Accountability Act compliant SHA-512 algorithm that minimizes re-identification risk. The authors subsequently linked individual records using a central honest broker with an algorithm that assigns weights to hash combinations in order to generate high specificity matches.
    Results
    The software application successfully linked and de-duplicated 7 million records across 6 institutions, resulting in a cohort of 5 million unique records. Using a manually reconciled set of 11 292 patients as a gold standard, the software achieved a sensitivity of 96% and a specificity of 100%, with a majority of the missed matches accounted for by patients with both a missing social security number and last name change. Using 3 disease examples, it is demonstrated that the software can reduce duplication of patient records across sites by as much as 28%.
    Conclusions
    Software that standardizes the assignment of a unique seeded hash identifier merged through an agreed upon third-party honest broker can enable large-scale secure linkage of EHR data for epidemiologic and public health research. The software algorithm can improve future epidemiologic research by providing more comprehensive data given that patients may make use of multiple healthcare systems.

    Keywords: Information; Customers; Safety; Rights; Ethics; Entrepreneurship; Health Care and Treatment; Health Industry; Chicago;

    Citation:

    Kho, Abel, John Cashy, Kathryn Jackson, Adam Pah, Satyender Goel, Jorn Boehnke, John Eric Humphries, Scott Duke Kominers, and et al. "Design and Implementation of a Privacy Preserving Electronic Health Record Linkage Tool in Chicago." Journal of the American Medical Informatics Association 22, no. 5 (September 2015): 1072–1080. View Details
  11. Multilateral Matching

    John William Hatfield and Scott Duke Kominers

    We introduce a matching model in which agents engage in joint ventures via multilateral contracts. This approach allows us to consider production complementarities previously outside the scope of matching theory. We show analogues of the first and second welfare theorems and, when agents' utilities are concave in venture participation, show that competitive equilibria exist, correspond to stable outcomes, and yield core outcomes. Competitive equilibria exist in our setting even when externalities are present.

    Keywords: matching; networks; joint ventures; stability; Competitive equilibrium; Core; Networks; Competition; Joint Ventures; Balance and Stability; Groups and Teams; Entrepreneurship;

    Citation:

    Hatfield, John William, and Scott Duke Kominers. "Multilateral Matching." Journal of Economic Theory 156 (March 2015): 175–206. View Details
  12. Big Data and Big Cities: The Promises and Limitations of Improved Measures of Urban Life

    Edward L. Glaeser, Scott Duke Kominers, Michael Luca and Nikhil Naik

    New, "big" data sources allow measurement of city characteristics and outcome variables at higher frequencies and finer geographic scales than ever before. However, big data will not solve large urban social science questions on its own. Big data has the most value for the study of cities when it allows measurement of the previously opaque, or when it can be coupled with exogenous shocks to people or place. We describe a number of new urban data sources and illustrate how they can be used to improve the study and function of cities. We first show how Google Street View images can be used to predict income in New York City, suggesting that similar image data can be used to map wealth and poverty in previously unmeasured areas of the developing world. We then discuss how survey techniques can be improved to better measure willingness to pay for urban amenities. Finally, we explain how Internet data is being used to improve the quality of city services.

    Keywords: Data and Data Sets; Urban Scope; City;

    Citation:

    Glaeser, Edward L., Scott Duke Kominers, Michael Luca, and Nikhil Naik. "Big Data and Big Cities: The Promises and Limitations of Improved Measures of Urban Life." Economic Inquiry (forthcoming). View Details
  13. The Growing Problem of Patent Trolling

    Lauren Cohen, Umit Gurun and Scott Duke Kominers

    The last decade has seen a sharp rise in patent litigation in the U.S., with 2015 having one of the highest patent lawsuit counts on record. In theory, this could be a consequence of growth in the commercialization of technology and innovation—patent lawsuits increase as more firms turn to intellectual property (IP) protection to safeguard their competitive advantages. However, the majority of recent patent litigation is driven by nonpracticing entities (NPEs), firms that generate no products but instead amass patent portfolios for the sake of enforcing IP rights afforded therein. We discuss new, large-sample evidence adding to a growing literature suggesting that NPEs—in particular, large patent aggregators—on average act as "patent trolls," suing cash-rich firms seemingly irrespective of actual patent infringement. This has a negative impact on future innovation activity at targeted firms. These results suggest a need to check the power of NPEs through changes in U.S. IP policy, in particular to screen out trolling early in the litigation process.

    Keywords: Patent Aggregators; patent litigation; patent pools; Patent trolls; Patents; Lawsuits and Litigation; United States;

    Citation:

    Cohen, Lauren, Umit Gurun, and Scott Duke Kominers. "The Growing Problem of Patent Trolling." Science 352, no. 6285 (April 29, 2016): 521–522. (The Growing Problem of Patent Trolling • SCIENCE • VIDEO.) View Details
  14. Investment Incentives in Labor Market Matching

    John William Hatfield, Fuhito Kojima and Scott Kominers

    We provide an illustration of how the design of labor market clearing mechanisms can affect incentives for human capital acquisition. Specifically, we extend the labor market matching model (with discrete transfers) of Kelso and Crawford (1982) to incorporate the possibility that agents may invest in human capital before matching. We show that in this setting, the worker-optimal stable matching mechanism incentivizes workers to make (nearly) efficient human capital investments. En route to our main result, we show that so long as the space of salaries is sufficiently rich, every stable outcome in the Kelso and Crawford (1982) setting is approximately efficient.

    Citation:

    Hatfield, John William, Fuhito Kojima, and Scott Kominers. "Investment Incentives in Labor Market Matching." American Economic Review: Papers and Proceedings 104, no. 5 (May 2014): 436–441. View Details
  15. Delayed-Response Strategies in Repeated Games with Observation Lags

    Dan Fudenberg, Yuhta Ishii and Scott Kominers

    We extend the folk theorem of repeated games to two settings in which players' information about others' play arrives with stochastic lags. In our first model, signals are almost-perfect if and when they do arrive, that is, each player either observes an almost-perfect signal of period-t play with some lag or else never sees a signal of period-t play. The second model has the same lag structure, but the information structure corresponds to a lagged form of imperfect public monitoring, and players are allowed to communicate via cheap-talk messages at the end of each period. In each case, we construct equilibria in “delayed-response strategies,” which ensure that players wait long enough to respond to signals that with high probability all relevant signals are received before players respond. To do so, we extend past work on private monitoring to obtain folk theorems despite the small residual amount of private information.

    Keywords: "Repeated games"; Folk theorem; Private monitoring; Observation lag;

    Citation:

    Fudenberg, Dan, Yuhta Ishii, and Scott Kominers. "Delayed-Response Strategies in Repeated Games with Observation Lags." Journal of Economic Theory 150 (March, 2014): 487–514. View Details
  16. Stability and Competitive Equilibrium in Trading Networks

    John William Hatfield, Scott Kominers, Alexandru Nichifor, Michael Ostrovsky and Alexander Westkamp

    We introduce a model in which agents in a network can trade via bilateral contracts. We find that when continuous transfers are allowed and utilities are quasi-linear, the full substitutability of preferences is sufficient to guarantee the existence of stable outcomes for any underlying network structure. Furthermore, the set of stable outcomes is essentially equivalent to the set of competitive equilibria, and all stable outcomes are in the core and are efficient. By contrast, for any domain of preferences strictly larger than that of full substitutability, the existence of stable outcomes and competitive equilibria cannot be guaranteed.

    Citation:

    Hatfield, John William, Scott Kominers, Alexandru Nichifor, Michael Ostrovsky, and Alexander Westkamp. "Stability and Competitive Equilibrium in Trading Networks." Journal of Political Economy 121, no. 5 (2013): 966–1001. View Details