Thesis advisor: Arthur Lewbel / In this series of essays, I apply the tools of economics to a variety of real world problems. The first essay looks at the impact of a gun control regulation on mortality and crime. A third of US states have removed all restrictions on carrying concealed handguns. This might decrease crime by invisibly arming law-abiding citizens, or increase it by eliminating penalties for criminals. It could have no effect at all, because handguns are easily hidden, so anyone who wished to carry a gun was already doing so. I compare counties along the borders of states that liberalized concealed carry to contiguous counties in neighboring states that did not, using mortality and crime micro-data. I find that deregulation had no impact on homicide, violent crime, firearm mortality, firearm usage, or firearm ownership. The second essay, co-authored with Sajala Pandey, looks at the impact of an earthquake in Nepal on child development. Biologists have posited that prenatal maternal stress (PNMS) has an adverse impact on child development, possibly via the process of epigenetic imprinting which occurs during the first trimester. Researchers have attempted to study this link by using natural disasters as a source of exogenous variation. A shortcoming of these studies is that natural disasters may also affect prenatal healthcare provision, either by decreasing it’s provision (due to infrastructure being destroyed) or increasing it (thanks to aid flowing into the region.) We look at the impact of 2015 Earthquake in Nepal on children who were (a) in utero at the time of the earthquake and (b) in areas severely affected by it. Consistent with theories from PNMS, we find that the earthquake adversely impacted their height-for-age, and the effects were concentrated on individuals who were in the first trimester of gestation. These negative effects were entirely offset by an increase in the consumption of antenatal healthcare. We find that the earthquake resulted in a improvement in development indicators for those children who were in severely affected areas but not in-utero at the time of the earthquake, highlighting the importance of healthcare provision in early childhood. The third essay, co-authored with Andrew Copland, proposes a solution to the problem of assigning multiple scarce goods to agents in the absence of prices, for example assigning seats in courses to students in a university. Students submit a list of preferences over courses, a lottery for rankings is held, and an algorithm allocates each student their top available course, reversing their ranks at the end of each round. Then, for each student, the algorithm compares their outcomes to the outcomes generated by every alternative ordering they could have set. Whenever such revisions result in more preferred outcomes, their preferences are replaced with the alternative. Our solution is non-dictatorial and Pareto optimal. When it converges without encountering a loop, it is strategy-proof. It retains properties even in small economies. We compare our algorithm to alternatives. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

This dissertation consists of three essays on microeconomics. The first essay considers matching markets, markets where buyers and sellers and concerned about who they interact with. It proposes a model to analyze these markets akin to the standard supply and demand framework. The second essay considers mechanism design, the problem of designing rules to make collective decisions in the presence of private information. It proposes the concept of strategyproofness in the large, which is that an agent without too fine information has negligible gains from misreporting her type in a large market. It argues that, for all practical purposes, this concept correctly separates mechanisms where behavior akin to price-taking is observed, and those where participants rampantly manipulate their stated preferences. A Theorem is proven that gives a precise sense in which strategyproofness in the large is not a very restrictive property. The third essay considers the evolutionary origins of the endowment effect bias, where the willingness to pay for a good is smaller than the willingness to accept. It gives evidence that this bias is not present in a modern hunter-gatherer population, questioning standard evolutionary accounts. It shows that cultural shocks in a subpopulation did give rise to the bias. / Economics

Thesis advisor: M. Utku Ünver / Thesis advisor: M. Bumin Yenmez / This thesis is a collection of three essays in market design concerning designs of matching markets, affirmative action schemes, and COVID-19 testing policies. In Chapter 1, we explore the possibility of designing matching mechanisms that can accommodate non-standard choice behavior. In the standard model of matching markets, preferences over potential assignments encode participants' choice behavior. Our contribution to this literature is introducing behavioral participants to matching theory's setup. We pin down the necessary and sufficient conditions on participants' choice behavior for the existence of stable and incentive compatible matching mechanisms. Our results imply that well-functioning matching markets can be designed to adequately accommodate a plethora of non-standard (and standard) choice behaviors. We illustrate the applicability of our results by demonstrating that a simple modification in a commonly used matching mechanism enables it to accommodate non-standard choice behavior. In Chapter 2, we show that commonly used methods in reserving positions for beneficiaries of affirmative action are often inadequate in settings where affirmative action policies apply at two levels simultaneously, for instance, at university and itsdepartments. We present a comprehensive evaluation of existing procedures and formally and empirically document their shortcomings. We propose a new solution with appealing theoretical properties and quantify the benefits of adopting it using recruitment advertisement data from India. Our theoretical analysis hints at new possibilities for future work in the literature on the theory of apportionment (of parliamentary seats). Chapter 3 delves into the designs of the commonly used and advocated COVID-19 testing policies to resolve a conflict between their allocative efficiency and the ability to identify the infection rates. We present a novel comparison of various COVID-19 testing policies that allows us to pin down ordinally efficient testing policies that generate reliable estimates of infection rates while prioritizing testing of persons suspected of having the disease. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

This thesis comprises four essays in the economics of networks and market design. The common thread in all these essays is the presence of complementarities or externalities. Chapter 2 presents a unified model of networks and matching markets. We build on a contribution by Pycia (2012). We show that strong pairwise alignment of agents’ preferences is a necessary and sufficient condition for the existence of strongly stable networks and strongly stable allocations in multilateral matching markets with finite contracts. Strongly stable networks are not necessarily efficient. Although we use a demanding stability concept, strong pairwise alignment allows for complementarities and externalities. In Chapter 3, we generalise the gross substitutes and complements condition introduced by Sun and Yang (2006). Our new condition guarantees the existence of competitive equilibrium in economies with indivisible goods. Competitive equilibrium can be found using an extension of the double-track adjustment process (Sun and Yang, 2009). In this chapter, we also study contract networks (Ostrovsky, 2008). We show that chain-stable contract allocations can exist even in cyclical contractual networks, such as electricity markets, as long as they are appropriately segmented. In Chapter 4, we run a series of experiments to compare the performance of four auctions – first-price, Vickrey, Vickrey-Nearest Rule (Day and Cramton, 2008), and Reference Rule (Erdil and Klemperer, 2010). In our setting, there are two items and three bidders. Two local bidders want an item each, but the global bidder wants both items. We introduce various exposure and package-bidding treatments. We find that the first-price auction always revenue-dominates all the other auctions without any loss in efficiency, strengthening the results of Marszalec (2011). Exposure affects global bidders only in the first-price auction. In other auctions, global bidders often do not take into account the effect of their own bids on their payments. We find no evidence of threshold effects. Finally, in Chapter 5, we develop a new model of online social network formation. In this model, agents belong to many overlapping social groups. We derive analytical solutions for the macroscopic properties of the network, such as the degree distribution. We study the dynamics of homophily – the tendency of individuals to associate with those similar to themselves. We calibrate our model to Facebook data from ten American colleges.

Apresentamos a teoria sobre mercados de dois lados, centralizados e descentralizados, para analisar o mercado de admissão de estudantes aos Centros de Pós-graduação em Economia no Brasil ao longo dos últimos 15 anos. Iniciamos descrevendo a história da organização deste mercado até a época atual. As falhas do sistema descentralizado e as hipóteses sobre o insucesso do procedimento centralizado de 1997 são discutidas. Observações empíricas são utilizadas para propor um modelo teórico que represente aproximadamente o atual mecanismo descentralizado e explique a aparente duradoura aplicação desse mecanismo. Por fim, tecemos considerações a respeito das possibilidades de aprimoramento deste mercado com modificações do mecanismo existente. / We present the theory of two-sided matching markets, with centralized and decentralized mechanisms, in order to analyze a Brazilian market in which graduated students seek positions in postgraduate programs in economics. We first describe the institutional history of this market. The failures of the decentralized procedure and the hypothesis about the failure of the 1997 centralized mechanism are discussed. Empirical observations are used to propose a theoretical model that represents the actual decentralized matching procedure of the market. Based in this model we explain the apparent long-lasting use of this decentralized mechanism. Finally, we make considerations about the possibilities of developments in this market by modifying the mechanism used today.

Apresentamos a teoria sobre mercados de dois lados, centralizados e descentralizados, para analisar o mercado de admissão de estudantes aos Centros de Pós-graduação em Economia no Brasil ao longo dos últimos 15 anos. Iniciamos descrevendo a história da organização deste mercado até a época atual. As falhas do sistema descentralizado e as hipóteses sobre o insucesso do procedimento centralizado de 1997 são discutidas. Observações empíricas são utilizadas para propor um modelo teórico que represente aproximadamente o atual mecanismo descentralizado e explique a aparente duradoura aplicação desse mecanismo. Por fim, tecemos considerações a respeito das possibilidades de aprimoramento deste mercado com modificações do mecanismo existente. / We present the theory of two-sided matching markets, with centralized and decentralized mechanisms, in order to analyze a Brazilian market in which graduated students seek positions in postgraduate programs in economics. We first describe the institutional history of this market. The failures of the decentralized procedure and the hypothesis about the failure of the 1997 centralized mechanism are discussed. Empirical observations are used to propose a theoretical model that represents the actual decentralized matching procedure of the market. Based in this model we explain the apparent long-lasting use of this decentralized mechanism. Finally, we make considerations about the possibilities of developments in this market by modifying the mechanism used today.