A Bayesian Dirichlet-Multinomial Test for Cross-Group Differences

Testing for differences within data sets is an important issue across various applications. Our work is primarily motivated by the analysis of microbiomial composition, which has been increasingly relevant and important with the rise of DNA sequencing. We first review classical frequentist tests that are commonly used in tackling such problems. We then propose a Bayesian Dirichlet-multinomial framework for modeling the metagenomic data and for testing underlying differences between the samples. A parametric Dirichlet-multinomial model uses an intuitive hierarchical structure that allows for flexibility in characterizing both the within-group variation and the cross-group difference and provides very interpretable parameters. A computational method for evaluating the marginal likelihoods under the null and alternative hypotheses is also given. Through simulations, we show that our Bayesian model performs competitively against frequentist counterparts. We illustrate the method through analyzing metagenomic applications using the Human Microbiome Project data.

Essays on State-Building and Sectarian Violence

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This dissertation seeks to explain the role of governmental and non-governmental actors in increasing/reducing the emergence of intergroup conflict after war, when group differences have been a salient aspect of group mobilization. This question emerges from several interrelated branches of scholarship on self-enforcing institutions and power-sharing arrangements, group fragmentation and demographic change, collective mobilization for collectively-targeted violence, and conflict termination and the post-conflict quality of peace. This question is investigated through quantitative analyses performed at the sub-national, national, and cross-national level on the effect of elite competition on the likelihood of violence committed on the basis of group difference after war. These quantitative analyses are each accompanied by qualitative, case study analyses drawn from the American Reconstruction South, Iraq, and Cote d'Ivoire that illustrate and clarify the mechanisms evaluated through quantitative analysis.

Shared findings suggest the correlation of reduced political competition with the increased likelihood of violence committed on the basis of group difference. Separate findings shed light on how covariates related to control over rent extraction and armed forces, decentralization, and citizenship can lead to a reduction in violence. However, these same quantitative analyses and case study analysis suggest that the control of the state can be perceived as a threat after the end of conflict. Further, together these findings suggest the political nature of violence committed on the basis of group difference as opposed to ethnic identity or resource scarcity alone.

Together, these combined analyses shed light on how and why political identities are formed and mobilized for the purpose of committing political violence after war. In this sense, they shed light on the factors that constrain post-conflict violence in deeply divided societies, and contribute to relevant academic, policy, and normative questions.

Restorative Justice and Political Forgiveness: A Comparative Study of Truth and Reconciliation Commissions

This research project involves a comparative, cross-national study of truth and reconciliation commissions (TRCs) in countries around the world that have used these extra-judicial institutions to pursue justice and promote national reconciliation during periods of democratic transition or following a civil conflict marked by intense violence and severe human rights abuses. An important objective of truth and reconciliation commissions involves instituting measures to address serious human rights abuses that have occurred as a result of discrimination, ethnocentrism and racism. In recent years, rather than solely utilizing traditional methods of conflict resolution and criminal prosecution, transitional governments have established truth and reconciliation commissions as part of efforts to foster psychological, social and political healing.

The primary objective of this research project is to determine why there has been a proliferation of truth and reconciliation commissions around the world in recent decades, and assess whether the perceived effectiveness of these commissions is real and substantial. In this work, using a multi-method approach that involves quantitative and qualitative analysis, I consider the institutional design and structural composition of truth and reconciliation commissions, as well as the roles that these commissions play in the democratic transformation of nations with a history of civil conflict and human rights violations.

In addition to a focus on institutional design of truth and reconciliation commissions, I use a group identity framework that is grounded in social identity theory to examine the historical background and sociopolitical context in which truth commissions have been adopted in countries around the world. This group identity framework serves as an invaluable lens through which questions related to truth and reconciliation commissions and other transitional justice mechanisms can be explored. I also present a unique theoretical framework, the reconciliatory democratization paradigm, that is especially useful for examining the complex interactions between the various political elements that directly affect the processes of democratic consolidation and reconciliation in countries in which truth and reconciliation commissions have been established. Finally, I tackle the question of whether successor regimes that institute truth and reconciliation commissions can effectively address the human rights violations that occurred in the past, and prevent the recurrence of these abuses.

Investing in the Homeland: Foreign Assets and Patterns of Immigrant Economic Incorporation

This dissertation consists of three separate studies that examine patterns of immigrant incorporation in the United States. The first study tests competing hypotheses derived from conflicting theoretical frameworks−transnational perspective and cross-national framework− to determine whether transnational engagement and incorporation are concurrent processes among Chinese, Indian, and Mexican immigrants. This study measures transnational engagement and incorporation as home and home country asset ownership using multi-panel, nationally representative data from the New Immigrant Survey (NIS) collected in 2003 and 2007. Results support a cross-border framework and indicate that transnational asset ownership decreases among all immigrant groups, while U.S. asset ownership increases. Findings from this study also indicate that due to disadvantaged pre-migration SES and low human capital, Mexican immigrants are less likely than other immigrants to own home country assets during the year after receiving their green card.

The second study examines the doubly disadvantaged position of elderly immigrants in the U.S. wealth distribution by applying the life course perspective to the dominance-differentiation theory of immigrant wealth stratification. I analyze elderly immigrant wealth in respect to U.S.-born seniors and younger immigrant cohorts using two data sets: the Survey of Income and Program Participation (SIPP) and the New Immigrant Survey (NIS). The Survey of Income and Program Participation (2001 to 2005) is a nationally representative survey of U.S. households. The first series of analyses reveals a significant wealth gap between U.S.- and foreign-born seniors which is most pronounced among the wealthiest households in my sample; however, U.S. tenure explains much of this difference. The second series of analyses suggests that elderly immigrants experience greater barriers to incorporation compared to their younger counterparts.

In the third study, I apply a transnational lens to the forms-of-capital and opportunity structure models of entrepreneurship in order to analyze the role of foreign resources in immigrant business start-ups. I propose that home country property use represents financial, social, and class resources that facilitate immigrant entrepreneurship. I test my hypotheses using survey data on Latin American immigrants from the Comparative Immigrant Entrepreneurship Project. Findings from these analyses suggest that home country asset ownership provides financial and social capital that is related to an increased likelihood of immigrant entrepreneurship.

Politics and Poetics of the Novel: Using Domesticity to Create the Nation

This thesis examines how the depiction of the family during war reinforces or challenges societal values in three nineteenth-century novels. The primary focus lies in three novels by Sir Walter Scott, Leo Tolstoy, and Harriet Beecher Stowe that represent the perspectives of England, Russia, and the United States, respectively, and their evolving nationalism as the roots of the Napoleonic Wars and the American Civil War became visible. By investigating the interaction between economic classes, it can be concluded that the preservation of the family is inherently dependent on social status in some nations, while in others, it is integral to daily life regardless of class. The backdrop of impending war only serves to heighten national differences, overturn the organization of the family hierarchy, and redefine the idea of the modern household.