Essays in Microeconomic Theory:

Thesis advisor: Mehmet EkmekciThis dissertation consists of two independent essays. In the first essay, Coordination in Complex Environments, I introduce a framework to study coordination in highly uncertain environments. Coordination is an important aspect of innovative contexts, where: the more innovative a course of action, the more uncertain its outcome. To explore the interplay of coordination and informational complexity, I embed a beauty-contest game into a complex environment. I uncover a new conformity phenomenon. The new effect may push towards exploration of unknown alternatives, or constitute a status quo bias, depending on the network structure of the connections among players. In the second essay, The Extensive Margin of Bayesian Persuasion, I study the persuasion of a receiver who accesses information only if she exerts attention effort. The sender uses the information to incentivize the receiver to pay attention. I show that persuasion mechanisms are equivalent to signals. In a model of media capture, the sender finds it optimal to censor high states.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics

Essays in Econometrics and Machine Learning:

Thesis advisor: Shakeeb KhanThesis advisor: Zhijie XiaoThis dissertation consists of three chapters demonstrating how the current econometric problems can be solved by using machine learning techniques. In the first chapter, I propose new approaches to estimating large dimensional monotone index models. This class of models has been popular in the applied and theoretical econometrics literatures as it includes discrete choice, nonparametric transformation, and duration models. A main advantage of my approach is computational. For instance, rank estimation procedures such as those proposed in Han (1987) and Cavanagh and Sherman (1998) that optimize a nonsmooth, non convex objective function are difficult to use with more than a few regressors and so limits their use in with economic data sets. For such monotone index models with increasing dimension, we propose to use a new class of estimators based on batched gradient descent (BGD) involving nonparametric methods such as kernel estimation or sieve estimation, and study their asymptotic properties. The BGD algorithm uses an iterative procedure where the key step exploits a strictly convex objective function, resulting in computational advantages. A contribution of my approach is that the model is large dimensional and semiparametric and so does not require the use of parametric distributional assumptions. The second chapter studies the estimation of semiparametric monotone index models when the sample size n is extremely large and conventional approaches fail to work due to devastating computational burdens. Motivated by the mini-batch gradient descent algorithm (MBGD) that is widely used as a stochastic optimization tool in the machine learning field, this chapter proposes a novel subsample- and iteration-based estimation procedure. In particular, starting from any initial guess of the true parameter, the estimator is progressively updated using a sequence of subsamples randomly drawn from the data set whose sample size is much smaller than n. The update is based on the gradient of some well-chosen loss function, where the nonparametric component in the model is replaced with its Nadaraya-Watson kernel estimator that is also constructed based on the random subsamples. The proposed algorithm essentially generalizes MBGD algorithm to the semiparametric setup. Since the new method uses only a subsample to perform Nadaraya-Watson kernel estimation and conduct the update, compared with the full-sample-based iterative method, the new method reduces the computational time by roughly n times if the subsample size and the kernel function are chosen properly, so can be easily applied when the sample size n is large. Moreover, this chapter shows that if averages are further conducted across the estimators produced during iterations, the difference between the average estimator and full-sample-based estimator will be 1/\sqrt{n}-trivial. Consequently, the averaged estimator is 1/\sqrt{n}-consistent and asymptotically normally distributed. In other words, the new estimator substantially improves the computational speed, while at the same time maintains the estimation accuracy. Finally, extensive Monte Carlo experiments and real data analysis illustrate the excellent performance of novel algorithm in terms of computational efficiency when the sample size is extremely large. Finally, the third chapter studies robust inference procedure for treatment effects in panel data with flexible relationship across units via the random forest method. The key contribution of this chapter is twofold. First, it proposes a direct construction of prediction intervals for the treatment effect by exploiting the information of the joint distribution of the cross-sectional units to construct counterfactuals using random forest. In particular, it proposes a Quantile Control Method (QCM) using the Quantile Random Forest (QRF) to accommodate flexible cross-sectional structure as well as high dimensionality. Second, it establishes the asymptotic consistency of QRF under the panel/time series setup with high dimensionality, which is of theoretical interest on its own right. In addition, Monte Carlo simulations are conducted and show that prediction intervals via the QCM have excellent coverage probability for the treatment effects comparing to existing methods in the literature, and are robust to heteroskedasticity, autocorrelation, and various types of model misspecifications. Finally, an empirical application to study the effect of the economic integration between Hong Kong and mainland China on Hong Kong’s economy is conducted to highlight the potential of the proposed method.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics

Pseudo-Anosov maps and genus-two L-space knots:

Thesis advisor: John A. BaldwinWe classify genus-two L-space knots in S3 and the Poincare homology sphere.This leads to the first and to-date only detection results in knot Floer homology for knots of genus greater than one. Our proofs interweave Floer-homological properties of L-space knots, the geometry of pseudo-Anosov maps, and the theory of train tracks and folding automata for braids. The crux of our argument is a complete classification of fixed-point-free pseudo-Anosov maps in all but one stratum on the genus-two surface with one boundary component. To facilitate our classification, we exhibit a small family of train tracks carrying all pseudo-Anosov maps in most strata on the marked disk. As a consequence of our proof technique, we almost completely classify genus-two, hyperbolic, fibered knots with knot Floer homology of rank 1 in their next-to-top grading in any 3-manifold. Several corollaries follow, regarding the Floer homology of cyclic branched covers, SU(2)-abelian Dehn surgeries, Khovanov and annular Khovanov homology, and instanton Floer homology.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Mathematics

Essays on Gender Differences in Job Search Beliefs and Behavior:

Thesis advisor: Lucas CoffmanGender Differences in Sorting on the Job Market: The Role of Application Costs Research shows that, holding qualifications equal, women are less willing than men to apply for certain high-paying jobs. Through a stylized labor market experiment, I investigate whether the "gender application gap" for high-paying jobs is affected by the presence or magnitude of application costs. I randomly vary the cost of applying for such a job, with subjects either facing no marginal cost, paying a fee, or writing a cover letter. Men are significantly more likely than equally qualified women to apply for a job only when the marginal cost of applying is zero. Introducing either type of application cost, but especially a fee, shrinks the gender application gap. This result comes from gender differences in self-selection behavior: women prefer not to apply when unskilled regardless of costs, whereas unskilled men only drop out of the applicant pool when a tangible cost is introduced. Women appear to face a higher cost than men from applying for a job they might perform poorly at, especially if the job is in a stereotypically "male-typed" domain. Subjective Self-Promotion and Gender Bias in Recruitment Previous work finds that women are more "modest" on average than equally skilled men when subjectively describing their abilities. If recruiters treat self-promotion by men and women as equally informative, they may become inefficiently biased towards male applicants. I randomly vary whether recruiters in a hiring experiment select from applicants who submitted only a resume, or submitted a resume and a cover letter (a type of subjective self-promotion). A cover letter requirement significantly reduces women's share of hires, even as it increases women's share of total applications. This hiring penalty against women cannot be explained by differences in qualifications or skills between men and women who choose to write cover letters. In fact, while employers see productivity gains from requiring a cover letter, such gains would be larger if cover letters did not bias recruiters towards male applicants. Textual analysis reveals that women’s cover letters contain half as much “boasting” language as men’s letters, which could help explain why cover letters impose a penalty on women's chances of getting hired. Anticipated Returns to "Clearing the Bar'': Gender Differences in Job Search Beliefs Conventional wisdom states that women are less willing than men to apply for a job for which they feel only partly qualified. Is this due to gender differences in anticipated returns to meeting or exceeding the desired level of qualification for a job? In a series of studies, I investigate whether men and women rate more and less qualified candidates’ chances of being hired differently. In the lab, I elicit beliefs about callback and offer likelihood by having subjects "bet" on the outcomes of other applicants' job searches. In a stylized online labor market experiment, I observe subjects' job application decisions and elicit beliefs regarding how qualified they will appear to a recruiter. Across studies, I find that women anticipate the same or greater returns than men to moving from "not at all" to "somewhat" qualified for a position, but the same or lower returns to moving from "somewhat" to fully or "highly" qualified. Controlling for gender differences in willingness to rate one's own or others' resumes as qualified does not change the pattern of results. Consistent with these findings, women in my experiment do not differ from men in how likely they are to apply if they fulfill some, but not all, of the listed qualifications in a job posting.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics

ARoman Catholic Account of the Flourishing and Virtuous Agency of People with Schizophrenia in the United States:

Thesis advisor: Stephen J. PopeThis dissertation develops a Roman Catholic account of the flourishing and virtuous agency of people with schizophrenia in the United States. At least two million people in the United States live with this brain disease, whose symptoms (e.g. delusions and avolition) complicate virtuous living. This dissertation remedies the neglect of schizophrenia in Catholic ethics and advances Christian ethics beyond the best available work done on the flourishing and virtuous agency of people with it by Protestant authors by: a) drawing its understanding of the content of human flourishing and of the theological and cardinal virtues from Christian theological and ethical commitments rather than from non-Christian sources; b) grounding the social supports that would increase the likelihood of clinical recovery and, therefore, of agency, habituation, virtue, and flourishing; c) showing via careful work in virtue theory whether, why, how, to what extent, and under which circumstances people with schizophrenia can live virtuously; and d) clarifying the meaning of the theological and cardinal virtues and their relevance for people with schizophrenia. Chapter One elucidates the challenges confronting people with schizophrenia in the United States from their illness itself and from the nation’s failed social response to them, as well as the opportunities available to them through clinical, functional, and personal recovery. Chapter Two concludes that, despite their liabilities, recent secular interpretations of the good life can or do conceptualize flourishing as possible even as constraints such as those associated with schizophrenia endure rather than only after they have been removed. Chapter Threes and Four find that Roman Catholic magisterial teachings about schizophrenia and an analogized reading of Luke 8:26-39 can helpfully ground necessary social supports, but the former requires greater conceptual clarification and development, while the latter emphasizes Jesus’s agency rather than that of the Gerasene man and depicts a total healing from total brokenness that is unavailable to or not fully representative of people with schizophrenia today. Chapter Five argues that Thomas Aquinas’s understandings of perfect and imperfect beatitude provide the best way for Christian ethics to conceptualize the possibility, content, and requirements of the flourishing of people with schizophrenia. Thomistic ethics can ground necessary social supports, and Aquinas’s virtue theory, as interpreted by William C. Mattison and developed by the scientifically-informed and socially-attuned threshold thesis, can show whether, why, how, to what extent, and under which circumstances people with schizophrenia can live virtuously before onset of illness, between onset and the threshold point of clinical recovery, and at and beyond the threshold. Chapters Six and Seven use Thomistic virtue ethics to explain the meaning of the theological and cardinal virtues, respectively, and their relevance for people with schizophrenia. The result is a wider and deeper Christian assessment of their possibilities for agency, habituation, virtue, and flourishing, even as schizophrenia’s challenges continue to varying degrees.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Theology

Three Essays in the Economics of Education:

Thesis advisor: Christopher BaumThis dissertation consists of three chapters studying topics in the economics of education. Chapter 1 investigates how changes in pension policies affect households' investments in their children's education. In China, elderly individuals receive financial support from their children, in addition to pension benefits and personal savings. The researchers used a difference-in-differences (DID) analysis to compare the investment behavior of households with enterprise employees (who were affected by the 1997 pension reform) and public sector employees (who were not affected) on household investments in human capital and savings. The results showed that households expecting lower pension benefits increased their investments in education by around 2%. Additionally, a 10% decrease in the pension replacement rate corresponded to a 1.1% rise in households' investments in human capital. The study also looked at the 2015 pension reform, which aimed to reduce pensions for public sector employees, but the increase in education investment among these employees was not statistically significant, possibly due to the gradual 10-year transition period. The findings suggest that when pension income is expected to decrease, households invest more in their children's human capital development to compensate. Chapter 2 studies how being admitted via affirmative action affects minority students in universities. This paper provides evidence on the effects of college admission preferential policy on students' self-perceptions, academic performance, and career intentions. We use regression discontinuity approach to compare students just below and above the cutoff with the same type of bonus points - ethnicity-based bonus points. Because of the bonus, students just below the cutoff may study in the same university as students above the cutoff. Therefore, we are able to eliminate the “peer effect”. Actual beneficiaries report negative self-perception compared with their peers, have lower college English test scores, and are less likely to get academic awards. As for their life plans, ethnicity-based beneficiaries are more inclined to find stable jobs and hope to get married sooner. Additionally, the placebo group in which students receive bonus points for academic achievements like math or physics Olympiad shows no impostor effects. These findings demonstrate that different categories of preferential policy have different effects on beneficiaries and provide insight into studying the impact of affirmative action in psychological aspect. Chapter 3 utilizes data from the China Family Panel Studies (CFPS) to investigate the effect of having a brother on women's educational attainment. The results indicate that gender discrimination persists in Chinese households' investment in human capital, with a significant negative impact of having a brother on women's education. The one-child policy, which limits family size and creates families without male offspring, has increased women's access to education by reducing competition with preferred siblings and decreasing opportunities for gender discrimination. The increase in women's average level of access to education since 1980s is the result of the combined effects of the reduction in the dilution of family resources and the reduction in opportunities for gender discrimination.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics

Share Pledging: The Costs and Benefits

Thesis advisor: Mary Ellen CarterThesis advisor: Amy HuttonManagerial share pledging (using shares as collateral for personal loans) is controversial. Institutional Shareholder Services (ISS), highly publicized anecdotes, and international research suggest that share pledging increases the risk of stock price crashes. Nevertheless, U.S. boards continue to allow the practice, suggesting that share pledging benefits shareholders or some boards are beholden to controlling managers who enjoy the private benefits of share pledging. Using a hand-collected dataset of share pledging by executives and directors of S&P 1500 firms from 2007-2020, I document three benefits-greater incentive alignment, reduced executive pay and lower voluntary executive turnover-while finding little evidence of increased crash risk. Interestingly, these benefits do not exist for firms with high managerial control. However ISS's 2012 policy denouncing share pledging did little to reduce share pledging among these firms. Instead the ISS policy increased negative shareholder votes at firms with both high and low managerial control with any share pledging, coinciding with a reduction in share pledging at firms with low managerial control, despite these firms enjoying benefits from share pledging. Overall my findings suggest that, for well-governed firms, managerial share pledging facilitates incentive alignment and lowers executive turnover and pay while not increasing stock price crash risk, calling into question efforts by ISS and others to curb the practice for all firms.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Carroll School of Management.Discipline: Accounting

AMultimethod Approach to Understanding Emerging Adult and Parent Management of Congenital Heart Disease:

Thesis advisor: Christopher S. LeeBackground: Congenital heart disease (CHD) is the most prevalent birth defect in the United States. Advances in treatment have changed CHD from what once was almost always a life-threatening condition to what is commonly a lifelong chronic condition. Up to 60% of adults with CHD experience large gaps in cardiology care during the transition from pediatric to adult specialty care. Effective CHD management in emerging adulthood maximizes lifelong potential, functioning and quality of life. Past research has failed to consider how emerging adults and their parents work together to manage CHD together as an interdependent team. Thus, there remains a dearth of information on how best to support emerging adults and their parents. Since CHD is a life-long diagnosis there is a critical need to understand the ways in which emerging adults and their parents as primary care partners engage in behavior to manage CHD together. This manuscript dissertation had an overarching goal to develop a deeper understanding of emerging adult and parent contributions to the management of CHD. Methods: First, an integrative review summarized and evaluated the evidence of published and peer-reviewed literature regarding parental perspective of the emerging adult with CHD. Next, a cross-sectional quantitative hypothesis-generating pilot study investigating emerging adult and parent contributions to management of CHD was conducted. And finally, an exploratory qualitative study was completed to describe health care team provider perspectives on the experience of emerging adults and their parents in managing CHD. Results: These three manuscripts have the key following results: 1) parents have concerns about their emerging adult children with CHD related to their future, independence in self-care of CHD, including health care system navigation, 2) there was a positive correlation between emerging adult and parent contributions to self-care (management, monitoring and maintenance) of CHD, and in the domain of navigating the health care system, there was a weak and negative correlation (the more an emerging adult does, the less the parent contributes), and 3) providers in health care teams report differences in both emerging adult and parent factors that impact management, and that self-care in emerging adults with CHD is critical with known health care system barriers that need assessment and improvement to support this population. Conclusion: The constellation of these findings from the dissertation and past work help fill critical knowledge and research gaps in emerging adult and parent/care partner contributions to management of CHD. These findings support the much-needed future work to inform clinical care, research, and policy for emerging adults with CHD and parents to further improve health and quality of life for this population.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Connell School of Nursing.Discipline: Nursing

Counting differentials with fixed residues:

Thesis advisor: Dawei ChenWe investigate the count of meromorphic differentials on the Riemann sphere pos-sessing a single zero, multiple poles with prescribed orders, and fixed residues at each pole. Gendron and Tahar previously examined this problem with respect to general residues using flat geometry, while Sugiyama approached it from the perspective of fixed-point multipliers of polynomial maps in the case of simple poles. In our study, we employ intersection theory on compactified moduli spaces of differentials, enabling us to handle arbitrary residues and pole orders, which provides a complete solution to this problem. We also determine interesting combinatorial properties of the solution formula. This thesis is organized as follows: In Chapter 1 we give an introduction to the problem and summarize the main results obtained. In Chapter 2 we review the compactification of moduli spaces of differentials and introduce various divisor classes. In Section 2.3 we explain how to identify the universal line bundle class with the divisor class of the locus of differentials satisfying a general given residue tuple and prove Theorem 1.0.1 (i). In Section 2.4 we impose exactly one independent partial sum vanishing condition to the residues and prove Theorem 1.0.1 (ii). In Section 2.5 we give a polynomial expression in terms of the zero order for the degree of mixed products between powers of the dual tautological class and the psi-class of the zero. Finally in Chapter 3 we prove Theorem 1.0.2 for arbitrary residues and investigate combinatorial properties of the solution formula. We have also verified our formula numerically for a number of cases by using the software package [CMZ2].Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Mathematics

Synthesis, Characterization, and Transformations of α-Borylcarbonyl Compounds Containing 1,2-Azaborine:

Thesis advisor: Shih-Yuan LiuThesis advisor: Marc SnapperOrganoboron compounds are widely used in organic synthesis and medicinal chemistry. It has been shown that organoboron compounds can undergo a vast quantity of transformations, especially stereospecific reactions. Boron enolates and their reactivity are less explored in the field of organic chemistry. In enolates, boron can be bound to oxygen or carbon. The boron-carbon enolates are of interest for having the potential to engage in stereospecific organoboron chemistry via the stereospecific carbon connected to the boron atom. Two methods of synthesizing boron-carbon enolates are through quaternized and unquaternized boron centers. While quaternized boron-carbon enolates are more studied, unquaternized boron-enolates represent a gap in the field. To date only four unquaternized boron-carbon enolates have been isolated and characterized with only one of the compounds engaging in organoboron chemistry. Herein I report the synthesis, isolation, and characterization of a boron-carbon enolate containing 1,2-azaborine as the organoboron analog.Thesis (MS) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Chemistry