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Essays in Econometrics and Machine Learning:
Full text linkThesis 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
Components of Quality of Delivery in Task-Shared, Psychosocial Interventions: Fidelity and Competence of Nonspecialist Providers in Rwanda
No full textThesis advisor: Theresa BetancourtFamilies in low- and middle-income countries (LMICs) face significant mental health and psychosocial care gaps. In recent years, researchers and practitioners have addressed these gaps by task-sharing evidence-based mental health and psychosocial support (MHPSS) interventions to nonspecialist community providers. Task-shared interventions have demonstrated effectiveness (improvements in MHPSS outcomes of intervention participants); however, quality of delivery (fidelity and competence) has rarely been examined as a factor associated with effectiveness despite implementation science models suggesting a causal link between quality of delivery and effectiveness. In this study, I apply a mixed methods approach to examine the quality of delivery by nonspecialists who are facilitating an evidence-based, early childhood development and family violence prevention program, known as Sugira Muryango, in Rwanda. Currently, Sugira Muryango is being expanded and implemented through the Promoting Lasting Anthropometric Change and Young Children’s Development (PLAY) Collaborative, which scales up Sugira Muryango to 10,000 households living in extreme poverty in Ngoma, Nyanza, and Rubavu districts. The program has strong ties to the Rwanda National Government and their social protection and policy goals.
I find that nonspecialist age is significantly associated with higher initial fidelity and competence scores and smaller improvements in fidelity and competence over time. In addition, nonspecialists in Nyanza district were more likely to have higher initial fidelity and competence scores but also see smaller changes over time. Fidelity and competence were found to significantly co-vary. Multi-level growth models revealed that fidelity was not a significant predictor of changes in any child discipline outcomes or of any responsive caregiving outcomes. However, competence significantly predicted changes in some responsive caregiving practices, specifically acceptance and learning materials, and it predicted decreases in physical punishment. In semi-structured interviews, the nonspecialists provided examples of using skills such as rapport-building, empathy, and active listening to deliver Sugira Muryango effectively. Nonspecialists also provided examples of barriers to quality of delivery, including compensation and technology issues. Overall, this dissertation contributes empirical evidence to what we understand theoretically and moves towards development of best practices for monitoring and supervising nonspecialists in task-shared MHPSS interventions.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Social Work.Discipline: Social Work
On the Minos:
Full text linkThesis advisor: Robert C. BartlettThis thesis is a study of Plato’s Minos, the subject matter of which is law. The dialogue depicts Socrates conversing with an anonymous companion, and it begins with Socrates abruptly asking the companion “what is law for us?” The question that sets the Minos in motion culminates in a perplexing answer: law wishes to be the discovery of what is. The first part of this thesis examines the portion of the dialogue that leads up to the aforementioned definition of law; in particular, it looks at what the definition suggests about law, and its relation to the other definitions (of which there are two) that precede it. The second part turns to the companion’s response to the third definition, which changes the course of the dialogue from an attempt to answer the opening question to a defense of an altered version of the third definition—that law is the discovery of what is. This section of the dialogue comprises two attempts made by Socrates to defend, or prove, that version of the third definition. Both of these proofs ultimately fail, but their failure, that is, the reason for their failure, shows why law can only wish to be the discovery of what is. The third part focuses on the third and final proof of the altered version of the third definition, which comes in the form of a defense of the titular Minos’ laws. The success of this proof, which persuades the companion of the altered version of the third definition, indicates what can be attained by law in light of the inadequacy revealed in the dialogue. By drawing out our expectations for law, and demonstrating the chasm between those expectations and what is possible, the Minos clarifies the limits of law; at the same time, by showing why law falls short, it also points beyond law. In this way the Minos indicates the common ground shared between politics and philosophy—and the latter’s superiority.Thesis (MA) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Political Science
Essays in Industrial Organization:
No full textThesis advisor: Michael GrubbThesis advisor: Charles MurryThis dissertation consists of two self-contained papers that explore the Industrial Organization of the UK television broadcasting market and broadband procurement by US K-12 schools Chapter 1: Welfare Effects of Competition in the UK Television Broadcasting Market In this chapter, I study the consumer welfare effects of a regulation that ended the exclusivity of telecast rights of live English Premier League games and induced entry into the UK television broadcasting market. Historically rights were owned by a single broadcaster. The regulation divided the games into mutually exclusive bundles and stipulated that a single broadcaster cannot own rights to all of them. This resulted in a new channel entering the market and showing some games. I estimate a model of household viewing preferences, channel subscription demand, and pricing using proprietary viewing and subscription choice data. Simulations show a 6.4\% (\pounds 10m per season) decline in consumer surplus driven by the higher prices consumers had to pay to view all the live games. This offset increased surplus from new content on the entrant channel. I propose an alternate regulation that breaks the exclusivity of games telecast on a channel and show that the estimated surplus could have been 29\% higher. Chapter 2: Bundling Demand in K-12 Broadband Procurement In this chapter coauthored with Gaurab Aryal, Charles Murry and Pallavi Pal, we evaluate the effects of bundling demand for broadband internet by K-12 schools. In 2014, New Jersey switched from decentralized procurements to a new procurement system that bundled schools into four regional groups. Using an event study approach, we find that, on average, prices for participants decreased by one-third, and broadband speed purchased increased sixfold. We bound the change in school expenditures due to the program and find that participants saved at least as much as their total ``E-rate" subsidy from the federal government. Under weak assumptions on demand, we show that participating schools experienced large welfare gains. Using an informal model and simulations, we analyze the main mechanisms that could lead to lower prices in the regional auctions.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics
An Amygdalar - Insular - Prefrontal Circuit Mediating Social Affective Behavior:
Full text linkThesis advisor: John P. ChristiansonThe perception of others as safe or threatening informs how we respond to others in a social setting. These social affective behaviors require the detection of sensory stimuli and the appraisal of others’ affective states to orchestrate adaptive behavioral responses. This process is also informed by one’s own internal state and environment. The neural circuitry underlying this behavior consists of a wide network of brain regions that communicate to execute social behaviors. However, the neural mechanisms mediating social affective behavior require further investigation. Therefore, the objective of this dissertation is to add detail to our understanding of the specific brain circuits involved in social affective behavior. The insula is a key node within this circuitry, necessary for approach and avoidance behaviors in a social affective preference (SAP) test where adult rats prefer interactions with stressed juveniles but avoid interactions with stressed adults. Here, I investigated the roles of a basolateral amygdala projections to the insula and insular projections to the PL in SAP testing and present evidence indicating the necessity of both these tracts to social affective behaviors. The results described here along with the reviewed literature support a potential amygdalar-insular-prefrontal circuit responsible for detecting social valence, integrating external stimuli with internal states, and selecting and executing context-appropriate social affective behaviors.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Psychology and Neuroscience
Respectful Patient-Provider Communication and Portal Use in Pregnant People of Color:
No full textThesis advisor: Joyce EdmondsBackground: Systemic racism contributes to the persistent and large inequities in perinatal health outcomes for pregnant people of color, particularly Black pregnant people. Poor communication between pregnant people of color and their providers contributes to these health inequities and perpetuates systemic racism in perinatal health. Pregnant people of color report being dismissed, ignored, discriminated against, and disrespected within the perinatal care system. One of the ways that patients communicate with their providers is via the patient portal. According to the Health Information National Trends Survey, around 80% of U.S. adults utilized information technology, such as patient portals, to track health data or communicate with their provider. Researchers have identified lower usage of patient portals in pregnant people of color compared to their White counterparts. Lower levels of utilization may perpetuate the digital divide for the low-resourced communities of color. Aims: The dissertation has three aims. The first aim was to synthesize and critically analyze patient-provider communication in pregnant people of color. The second aim was to examine the relationship between the quality of patient-provider communication (PPC) and the extent of patient portal use in pregnant people of color and to determine if digital health literacy is a moderating factor in this relationship. The third aim was to explore pregnant people of color’s access, use and perceptions of the patient portal in order to identify barriers and facilitators to quality digital communication with their prenatal providers.
Methods: An integrative review method was applied to the empirical literature to achieve aim one. A multi-method, cross-sectional survey study with a non-probability convenience sample of 130 pregnant people of color receiving prenatal care at a large safety net hospital in Boston was conducted for aims two and three. Logistic regression and moderation models were utilized to analyze the quantitative survey data to achieve the second aim. Content analysis was used to analyze the responses to four open-ended survey questions to achieve the third aim.
Results: A three-manuscript dissertation was completed. In the first manuscript, 26 articles were identified and the factors, outcomes and recommendations from communication between pregnant people of color and their prenatal providers were evaluated. There were two overarching themes: Racism and Discrimination and Unmet Information Needs along with multiple factors, outcomes and recommendations. The second manuscript reported on the quantitative results responses from 130 pregnant people of color. Participants that did not use the patient portal and who had public insurance had lower odds of rating higher quality PPC. Digital health literacy was found to be a moderating factor in the association between PPC and portal use at the level of portal users. The third manuscript reported on the content analysis and found main facilitators to communication between pregnant people of color and their providers were Provider behaviors and functionality of myChart and barriers were quality of response, multiple providers and digital access and literacy.
Conclusions: The findings from this dissertation may be translated into clinical practice by informing perinatal providers on the pregnant people of color’s ratings of respectful communication and facilitators and barriers to quality health communication. Policies and strategies may be developed to improve digital health communication in order to provide inclusive and person-centered care in pregnancy.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Connell School of Nursing.Discipline: Nursing
Cultivating Insight Through Comparing Cycles: How Comparison with the Hindu Kali Tradition Can Enrich the Christian Understanding of Life, Death, and Resurrection
No full textThesis advisor: Catherine CornilleThe Christian ecological tradition rejects problematic dualisms that separate and hierarchically value the body and soul, humans and creation, man and woman, etc. Ecofeminist theology seeks to provide alternatives that better recognize the interconnectedness of life overall, yet it has not fully responded to the dualism of life and death. This is evident in the work of Ivone Gebara, a leading ecofeminist theologian who addresses life, death, and resurrection within a more immanent understanding of the Trinity. Though she argues for a more ambiguous understanding of good and evil, creation and destruction, life and death, the tensions between these categories are never fully resolved. This is where the Hindu tradition, and in particular the Kali tradition of Hinduism, may shed new light on the Christian understanding of death as part of creation and of its interconnection with all life. The goddess Kali in particular is often referred to as the mistress of death, or death itself, and as such she does not protect her devotees from the inevitability of life, suffering, and death. Instead, Kali reveals the mortality of all life and frees devotees to embody their own fate and accept their own death as she grants them liberation from samsara (the continuous cycle of dying and rebirth into the world of materiality). Gebara advocates against hierarchical dualisms of good and evil, creation and destruction, life and death, where Kali already embodies the tension of these polarities, even the transcendence of them altogether. Even though there are fundamental differences between Hindu and Christian worldviews and conceptions of the divine, the figure of Kali addresses traditional tensions between life and death and between creation and salvation, and thus inspires a more integral liberation for all creation.Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Theology
ATheological-Ethical Analysis of Nigeria's Underdevelopment and the Role of the Catholic Archdiocese of Abuja as a Structure for Integral Development:
No full textThesis advisor: James KeenanNigeria is richly endowed with an array of natural resources and human capital. It is unarguably the largest economy in Africa, with an estimated 2023 gross domestic product (GDP) of $477.38 Billion. However, the superlative epithets of Nigeria with glaring upside economic potential are marginal vis-à-vis concrete socio-economic and demographic benchmarks such as per capita gross domestic product, life expectancy, Human Development Index (HDI), and the development paradigm of Catholic Social Teaching (CST) such as access to food and potable water, housing, employment, human rights, and security. This dissertation seeks to provide a hermeneutic for understanding Nigeria’s developmental quandaries as well as a solution. Drawing from Catholic Social Teaching (CST), Liberation Theology, and insights from critical realism, it argues that the tripartite concepts of developmentalism, assistentialism, and social structures are key to unraveling the origin and presence of Nigeria’s development challenges. Undergirding the proximate causes of Nigeria’s underdevelopment, such as egocentrism, tribalism, violent conflicts, and corruption, and the remote causes, such as developmentalism and assitentialism, are some impersonal mechanisms that incentivize, condition, sustain, and perpetuate factors of underdevelopment in Nigeria. Additionally, the notion of development that Nigeria adopted shortly after independence put Nigeria on the trajectory of underdevelopment and mis-development, which is evident today. Catholic social teaching, while cautioning against the dangers of a restrictive notion of development, offers a notion of development that is integral and genuine. The anthropological presuppositions of CST make it well-suited for development in the Nigerian context. This work seeks to demonstrate ways in which Catholic Social Teaching, given its interdisciplinary character, provides for a program of integral development in Nigeria through the Catholic Church. While it is the proper function of government to provide a program of development for its citizens, this work will contend that the Catholic Church in Nigeria, but even more so, the Archdiocese of Abuja, given its strategic location within the Federal Capital Territory, its historical relational trust and accountability and equipped with the theological language of CST and Liberation Theology can contribute to the development of Nigeria.Thesis (STD) — Boston College, 2024.Submitted to: Boston College. School of Theology and Ministry.Discipline: Sacred Theology
Protecting Endangered Species in the United States: A Historical Analysis of Reactive Environmental Law and Public Resistance
No full textThesis advisor: Prasannan ParthasarathiThis thesis is a historical analysis of the various modes of thinking that developed in response to the Endangered Species Act of 1973. What was originally a law that received wide support from the government and the public soon became one of the most controversial environmental laws in the United States. Utilizing congressional hearings, government records, laws, legal cases, newspaper articles, photographs, and public surveys, this study rejects the common conception that economic self-interest was the sole driver of opposition to the Act. It argues, instead, that the reactive and narrow framework of the law fueled criticism. People responded negatively to the law's lack of proactive, long-term thinking and the consequent implications for short-term economic growth. This reactive approach to environmental legislation is a common trend in the United States, continuing to fuel the political partisanship and polarization of environmental movements across the nation.Thesis (BA) — Boston College, 2024.Submitted to: Boston College. Morrissey School of Arts and Sciences.Discipline: History.Discipline: Scholar of the College
Nanoscale experimental and numerical investigations of novel photonic devices:
No full textThesis advisor: Michael J. NaughtonFor many centuries, physicists and engineers have explored the creation, manipulation and detection of light. Only within the past century, however, have fabrication techniques advanced to the point where individual photons can be generated, manipulated, and measured. These advances have brought us to the point we are at today, where photonic devices are set to revolutionize the fields of computing, sensing and quantum information, to name a few. Despite the promise of these devices, scientists are still working to fully understand the light-matter interactions that govern their behavior. In this thesis, we uniquely characterize the behavior of certain photonic devices in an effort to understand the underlying physical principles that define them. Of particular interest to us is imaging via near-field scanning optical microscopy (NSOM) of photonic integrated circuit (PIC) elements with high quality factors (Q), such as microring resonators and photonic crystal cavities (PhCs). While these elements are becoming ubiquitous in emerging PIC designs, they have remained difficult to accurately image due to their high sensitivity to small perturbations (i.e. the NSOM probe). We solve this problem by controllably modulating the NSOM tip-sample distance and reducing the size of the probe. Finite element model computer simulations demonstrate that both of these adjustments decrease the tip sample interaction. We then apply this knowledge to generate first of their kind 50 nm resolution NSOM images of high Q resonant PIC devices. Importantly, aside from being accurate, the proposed NSOM technique is also facile and non-destructive. In addition to local field exploration of PIC elements, we explore non-classical optical transmission through sub-wavelength apertures in metallic films. We demonstrate that these interesting features arise from photonic wave interference. Thesis (PhD) — Boston College, 2024.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Physics