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 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

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 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

Brotherhood and unity: Exploring language and nationalism in Yugoslav primers, 1941-1992

Thesis advisor: Gerald M. EasterThesis advisor: Margaret ThomasNationalism and national identity are abstract yet extremely powerful forces that can be at once a source of cohesion and faction. And a government’s ability to harness or rein-in these powers can be a crucial factor to its longevity, lest it be overcome by them on other fronts. These concepts—along with nation itself—are an amalgam of many elements that can include culture, economics, geography, history, language, politics, religion, etc., and the importance of a particular element can vary from group to group. In this dissertation, the focus is on the salience of language as an essential element of national identity, and the exploration of this topic has been done through an analysis of elementary language primers from 1941 through 1992 from the region known for a majority of that time as Yugoslavia. I argue that we can measure how important governments think language is as a component of a particular national identity by seeing how they treat and utilize—even instrumentalize—the language or languages spoken in their territory. This direct governmental use of language as a tool is particularly important in revealing how that government connects language to the national identity(-ies) in question. Certainly language policy and laws passed by a government to bolster or limit a particular language’s use can tell us a lot—in a very straightforward and overt way—about what that government sees as important; but, there is another more subtle—yet potentially more long-lasting—thing that can strengthen these efforts even further: teaching children. Looking at educational materials, in this case elementary language primers, can provide insight into what the government thinks is important with respect to its national identity. This analysis, done within a framework that focuses on three historical periods in the history and development of Yugoslavia, shows that governments do use language primers as a vehicle to promote and strengthen the nation, national identity, and national cohesion. We can be fairly confident that every book analyzed in this study was approved or published by the government where it was used; and, in each of the three historical periods that fall within the scope of this study, we see the goals of the state reflected in the language, content, and pedagogical methodology of the primers that were published during a given period.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Political Science

The Impact of Narcissistic CEOs Running Media Companies on Stock Markets: A Case Study on Elon Musk's Twitter Activity on the Performance of Tesla and Twitter

Thesis advisor: Donald CoxDoes a CEO’s narcissism influence the company’s stock? Would it matter if it is a media company? The Efficient Market Hypothesis claims that it matters little given market efficiency, as narcissism has been priced in stock based on the Capital Asset Pricing Model. Existing literature is divided on whether CEO narcissism influences corporate efficiency. This paper refines assumptions on asset pricing by indicating when market inefficiency occurs through panel studies, which the Adaptative Market Hypothesis overlooks. A case study on Elon Musk suggests that the CEO’s narcissism with media involvement creates temporary market inefficiency. This paper innovatively combines an event study of Elon Musk's Twitter activities on Tesla and Twitter with a panel analysis of 17 S&P 500 CEOs. The finding shows that younger and female CEOs, who derive narcissism supply and lead media companies, are more inclined to take risks on stock returns. This result suggests re-evaluating stock market efficiency to include CEO demographics and personality, which extends beyond traditional CAPM models.Thesis (BA) — Boston College, 2024.Submitted to: Boston College. Morrissey School of Arts and Sciences.Discipline: Economics.Discipline: Departmental Honors

Social Determinants and Biosocial Consequences of Depressive Symptoms: Analyzing Social Capital, Depression, and Cognition in Later Life

Thesis advisor: Sara M. MoormanThis dissertation explores the complex relationship between social capital and depressive symptoms across the life course, focusing particularly on the increasing prevalence of depression from mid-to-late life. Using a life course perspective, this research investigates how social determinants, such as social capital, shape the emergence, increase, and decrease of depressive symptoms as individuals age. Drawing from both the tangible and psychological dimensions of social capital, this dissertation examines how changes in social connections and networks influence depressive symptom outcomes, including the biosocial consequences of depression on cognitive function in later life. The research is divided into three analytical papers. The first paper analyzes longitudinal data to assess the association between social capital and depressive symptoms, distinguishing between within- and between-person effects. The second paper explores how depressive symptom subtypes evolve from midlife to later life, identifying distinct subtypes and examining the stability and transitions between them over time. The third paper investigates the relationship between depressive symptom subtypes, social capital, and cognitive function, exploring how depressive symptom subtypes may mediate this association. Findings across these studies emphasize the pivotal role of social capital in shaping depression outcomes, highlighting how social isolation and disconnection may exacerbate depressive symptoms in later life. This dissertation contributes to the sociology of mental health and aging by offering new insights into the social mechanisms underlying depression and its long-term impacts on cognitive function. Through this work, policymakers and health professionals may gain a deeper understanding of how targeted interventions aimed at enhancing social capital could mitigate the global burden of depression in aging populations.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Sociology

Decent Work and its Association with Mental and Physical Health among Latina Immigrants:

Thesis advisor: Betty S. LaiLatina immigrants comprise more than half of the 12.3 million immigrant women who work in the United States (U.S.) (American Immigration Council, 2017). However, they do not benefit from the same wages and workplace protections (i.e., decent work) as U.S.-born women. Latina immigrants are overrepresented in essential but low-wage jobs that are less likely to offer benefits like employee-sponsored health insurance and paid time off (U.S. Bureau of Labor Statistics, 2021). Yet, there is minimal research on the relationship between decent work and the physical and mental health of Latina immigrants, specifically. This is concerning, given that decent work is associated with positive physical and mental health outcomes (Duffy, Kim, et al., 2019; Duffy et al., 2021; Kozan et al., 2019). Using psychology of working theory (Duffy et al., 2016), LatCrit theory (Valdes, 1997), and mujerista psychology (Bryant-Davis & Comas-Díaz, 2016) as its frame, this study sought to address this gap in the literature through the examination of three research aims: identifying barriers to decent work specific to Latina immigrants (Aim 1); examining the relationship between decent work, physical health, and mental health (Aim 2); and testing moderation of these relationships by parental status (Aim 3). This study used a sub-sample of participants (n=591) from the 2019 National Health Interview Survey (NHIS), a nationally-representative survey conducted annually by the Centers for Disease Control and Prevention. Participants in the sub-sample were first-generation Latina immigrants between the ages of 18 and 78 (M = 43.92) who worked in the past week. The majority of the sub-sample identified as Mexican-American (55.30%) and non-U.S. citizens (52.12%). Data were analyzed using structural equation modeling (SEM). Results indicated that economic constraints significantly predicted decent work (Aim 1). Contrary to hypotheses, decent work did not predict physical health or mental health (Aim 2). Finally, residing with minor children strengthened the relationship between marginalization and decent work (Aim 3). Limitations and future directions for research, policy, and clinical practice are discussed.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Lynch School of Education.Discipline: Counseling, Developmental and Educational Psychology

Examining the Role of Vicarious Minority Stress within a Minority Stress Framework:

Thesis advisor: V. Paul PoteatSexual and gender minority (SGM) youth and young people have a significantly higher prevalence of mental health challenges than their heterosexual, cisgender peers (Jonas et al., 2022). These disparities are largely linked to disparate experiences of victimization, discrimination, and microaggressions (Meyer, 2003; Mongelli et al., 2019). While most of the literature on this association between minority stress and mental health outcomes focuses on direct experiences of minority stress such as discrimination and victimization, less attention has been given to indirect experiences of minority stress, such as reading about SGM-directed violence on the news or in social media (Hatzenbeuhler et al., 2019; Hicks, 2019; Hughto et al., 2021). Understanding the effects of these vicarious minority stressors, or instances of discrimination and stigma inflicted on someone who shares a minority identity, not in the presence of the individual and without directly targeting the individual, seems increasingly necessary. Recent studies suggest that vicarious experiences of discrimination affect SGM mental well-being across the country (Maduro et al., 2020). The current study sought to extend and test minority stress theory by assessing the impact of minority-specific vicarious stressors - in this case reading about an instance of identity-based community violence - on young peoples’ processing styles and mental health outcomes. In part 1 of the current study, I used an experimental design and quantitative text analysis to assess whether a diverse sample (N = 575) of SGM participants ages 18 - 24 (M = 22.45, SD = 2.22) exhibited differences in affect and processing style when asked to read and respond to a short passage depicting violence directed toward an individual who shares their SGM identities as opposed to those in the control, who read an identical passage with a heterosexual, cisgender subject. Results indicated a greater increase in negative affect, greater likelihood of using negative emotions and anger words, and greater use of self-reference words among participants exposed to the vicarious minority stressor. In part 2, I used structural equation modeling to assess whether self-reported past experiences of minority stress, identity affirmation, and critical consciousness predicted negative affect change and processing style among exposure group participants (N = 402), and whether these in turn predicted depressive symptoms. I found that negative affect change negatively predicted depressive symptoms and use of negative emotions words positively predicted depressive symptoms. Minority stress, identity affirmation, and critical consciousness positively predicted negative emotions words and indirectly predicted depressive symptoms via negative emotions words. Critical consciousness also positively predicted negative affect change and self-reference words, and negatively, indirectly predicted depressive symptoms via negative affect change. Implications to minority stress theory and therapeutic intervention are discussed.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Lynch School of Education.Discipline: Counseling, Developmental and Educational Psychology

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