Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
12 results
Search Results
Item The Impact of Leadership Practices on Teacher Retention in Maryland Public Charter and Contract Schools(2023) Carnaghan, Heather Elizabeth; Imig, David; Eubanks, Segun; Education Policy, and Leadership; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Teacher turnover imposes a significant negative impact on the education system as a whole, much to the detriment of student achievement. The Learning Policy Institute (2021) suggests this problem was exacerbated in all school settings by the global Covid-19 pandemic in which growing disparities between children and uncertainty about the future of public education has made the teacher’s role “more untenable than ever before”. Charter and contract schools face heightened challenges in regard to this phenomenon in retaining teachers, producing a high need for leadership practices that positively curb attrition. School leadership has the potential to implement change in response to environmental changes and work conditions, thus it is a critical catalyst for retention change. An extensive review of related research revealed that leadership practices can have a significant impact on populations that Ingersoll (2004) popularized as “movers, leavers, and stayers”, though little research existed specific to Maryland’s public charter and contract schools. The purpose of this study was to determine the leadership practices that Maryland public school teachers and leaders believe positively impact retention of teachers in the state. A survey was completed by 151 educators in which participants ranked the leadership practices they believed had the most positive impact on teacher retention at their schools. Categorical and ordinal responses were analyzed and a t-test was applied to determine significance of the differences between teacher and leader responses. Two focus groups were held to better understand the context of the survey findings. Sessions were transcribed and coded via open/emergent, axial, and selective coding. Two leadership practices were ranked in the top three by the vast majority of almost every generalized group and specialized subgroup: “Nurturing a Positive School Culture'' and “Cultivating Trusting Relationships”. No other practices came close to this level of selection by participants. While teachers and leaders agreed on the two foundational practices that increase retention, there was variance in the contextual answers given by each group regarding why that practice was necessary and how to implement it well. The literature, the teachers, and the leaders all pointed to charter and contract schools being “different”- different workloads, different visions, different challenges. Yet, this study finds that, despite differences in policy and demographics, public charter and contract schools share an essential commonality with traditional public schools; they retain teachers by cultivating trusting relationships and nurturing positive school environments.Item Reframing Children's Judgments of Consensus Reliability as a Process of Information Aggregation(2023) Levush, Karen Carmel; Butler, Lucas P; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Consensus is a compelling cue to the truth value of a given claim, but certain consensus patterns provide stronger evidence than others. This dissertation examines the developmental trajectory of children’s reasoning about the epistemic value of diverse perspectives for consensus’ reliability. One-hundred forty-four children between the ages of 7 and 9, as well as 48 adults, were introduced to a novel planet and alien groups that live there. Tasked with learning the “right things” about why various natural phenomena occur on this planet, participants were asked which one of two consensus groups, each of whom collectively thought something different, was the “better” group to ask. Participants rated their relative preference for one consensus group over another using a 6-point scale and were asked to explain their reasoning. These findings provide initial evidence that qualitative changes in children’s ability to consider how dependencies can lead to redundant information parallel the developmental shift in children’s appreciation for interpretive diversity in middle childhood.Item Corruption, Reform, and Revolution in Africa's Third Wave of Protest(2019) Lewis, Jacob Scott; McCauley, John F; Government and Politics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)What explains diverging calls for reform and revolution in Africa over the past ten years? African countries have made substantial strides toward actual democratic devel-opment, including a concerted effort to address corruption. As African democracies have strengthened, calls by citizens for anti-corruption reform have grown, highlighting the progress that is being made. Yet, in recent years, some anti-corruption movements have called instead for revolution - completely replacing the state or seceding altogether. What explains these calls for revolution? I argue that we need to understand how differ-ent types of corruption shape contentious goals. When corruption generates material benefits, citizens lose trust in politicians but do not lose trust in the system. In response, they call for reform, seeking to improve the system. When corruption generates system-ic benefits (distorting the system altogether), citizens lose trust in the institutions and instead call for revolution. I test this using individual-level data from survey experi-ments as well as large-n surveys, and group-level data using statistical analysis of pro-test events as well as case studies. I find strong support that types of corruption matter greatly in shaping contentious politics in Africa.Item Can voice harm team performance?: The role of relationship conflict and trust(2018) Baker, Bradley Edward; Chen, Gilad; Business and Management: Management & Organization; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Despite research substantiating the idea that when team members voice ideas and suggestions their team can perform better, some scholars have warned that voice can also harm team performance. Yet, our understanding of when, why, and how voice can undermine team functioning is still limited. Attempting to address these research gaps, I integrate and build on threat rigidity theory and regulatory focus theory to propose that the reason why voice has the potential to undermine team performance is because it can trigger relationship conflict – and that prohibitive voice, as compared to promotive voice, has a greater potential to trigger relationship conflict, especially when team trust is low. I test this theory using a time-lagged, laboratory study with 87 teams, as well as a time-lagged, multi-source field study with 49 teams of U.S. Air Force officers. Across studies, I largely do not find support for my hypotheses. For example, opposite of my predictions, it appears that both promotive and prohibitive voice have either a non-significant or negative effect on relationship conflict; however, I find partial support for the hypothesis that trust moderates the relationship between prohibitive voice and relationship conflict. Despite these mixed findings, this research contributes to the voice, teams, relationship conflict, and trust literatures by empirically investigating whether voice can undermine team performance.Item Factors in the Reporting of Unethical Conduct: The Importance of Trust in Leaders(2017) Norton, Michael Andrew; Lucas, Jeffey W; Sociology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)My research investigates factors related to the reporting of unethical conduct. While accounting for known individual, organizational and situational correlates, I focus particularly on leaders and especially on trust in leaders as whistle-blowing research to date has neglected the well-developed sociological literature of trust. Leveraging the benefits of multiple methods, I analyze recent secondary data on federal civilian employees, collect and analyze interview data at four civilian and military sites, and conduct a factorial vignette study to test factors and themes identified in the first two sections of my research. My secondary data analyses support previous whistle-blowing research in relating supervisor status, greater importance placed on anonymity, greater organizational support for anonymous reporting, greater organizational protection for whistle-blowers and greater severity of observed misconduct to increased reporting. Contrary to what previous literature theorizes, I find more observed leader misconduct and in-group location of misconduct relate to increased reporting. With the exception of an expressed in-group preference, my qualitative analyses reinforce these findings and identify a peer-oriented culture and self-preservation as reasons why unethical conduct may go unreported. My interview data also reveal that participants prefer to report unethical conduct to a trusted leader, although the severity of such misconduct may moderate this preference. My vignette analyses find greater trust in leaders is related to increased reporting only for non-supervisors, highlighting the additional importance trust plays for lower-status individuals. Also, good behavior by the leader accepting a report is related to increased reporting for all participants. My vignette data bolster previous findings, including relating a lesser orientation towards Machiavellianism to increased reporting, and find the severity of observed misconduct has the largest relative effect on the reporting outcome. Counter to my prediction, vignette participants are less likely to report unethical conduct perpetrated by a supervisor supporting the notion that fear of retaliation may factor into the reporting decision. By highlighting obstacles to reporting, I assist leaders in addressing such barriers possibly contributing to the identification and correction of unethical conduct. I conclude with implications for federal employees and all leaders seeking to increase the reporting of unethical conduct in their organizations.Item Security and Trust in Distributed Computation(2015) Liu, Xiangyang; Baras, John S; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We propose three research problems to explore the relations between trust and security in the setting of distributed computation. In the first problem, we study trust-based adversary detection in distributed consensus computation. The adversaries we consider behave arbitrarily disobeying the consensus protocol. We propose a trust-based consensus algorithm with local and global trust evaluations. The algorithm can be abstracted using a two-layer structure with the top layer running a trust-based consensus algorithm and the bottom layer as a subroutine executing a global trust update scheme. We utilize a set of pre-trusted nodes, headers, to propagate local trust opinions throughout the network. This two-layer framework is flexible in that it can be easily extensible to contain more complicated decision rules, and global trust schemes. The first problem assumes that normal nodes are homogeneous, i.e. it is guaranteed that a normal node always behaves as it is programmed. In the second and third problems however, we assume that nodes are heterogeneous, i.e, given a task, the probability that a node generates a correct answer varies from node to node. The adversaries considered in these two problems are workers from the open crowd who are either investing little efforts in the tasks assigned to them or intentionally give wrong answers to questions. In the second part of the thesis, we consider a typical crowdsourcing task that aggregates input from multiple workers as a problem in information fusion. To cope with the issue of noisy and sometimes malicious input from workers, trust is used to model workers' expertise. In a multi-domain knowledge learning task, however, using scalar-valued trust to model a worker's performance is not sufficient to reflect the worker's trustworthiness in each of the domains. To address this issue, we propose a probabilistic model to jointly infer multi-dimensional trust of workers, multi-domain properties of questions, and true labels of questions. Our model is very flexible and extensible to incorporate metadata associated with questions. To show that, we further propose two extended models, one of which handles input tasks with real-valued features and the other handles tasks with text features by incorporating topic models. Our models can effectively recover trust vectors of workers, which can be very useful in task assignment adaptive to workers' trust in the future. These results can be applied for fusion of information from multiple data sources like sensors, human input, machine learning results, or a hybrid of them. In the second subproblem, we address crowdsourcing with adversaries under logical constraints. We observe that questions are often not independent in real life applications. Instead, there are logical relations between them. Similarly, workers that provide answers are not independent of each other either. Answers given by workers with similar attributes tend to be correlated. Therefore, we propose a novel unified graphical model consisting of two layers. The top layer encodes domain knowledge which allows users to express logical relations using first-order logic rules and the bottom layer encodes a traditional crowdsourcing graphical model. Our model can be seen as a generalized probabilistic soft logic framework that encodes both logical relations and probabilistic dependencies. To solve the collective inference problem efficiently, we have devised a scalable joint inference algorithm based on the alternating direction method of multipliers. The third part of the thesis considers the problem of optimal assignment under budget constraints when workers are unreliable and sometimes malicious. In a real crowdsourcing market, each answer obtained from a worker incurs cost. The cost is associated with both the level of trustworthiness of workers and the difficulty of tasks. Typically, access to expert-level (more trustworthy) workers is more expensive than to average crowd and completion of a challenging task is more costly than a click-away question. In this problem, we address the problem of optimal assignment of heterogeneous tasks to workers of varying trust levels with budget constraints. Specifically, we design a trust-aware task allocation algorithm that takes as inputs the estimated trust of workers and pre-set budget, and outputs the optimal assignment of tasks to workers. We derive the bound of total error probability that relates to budget, trustworthiness of crowds, and costs of obtaining labels from crowds naturally. Higher budget, more trustworthy crowds, and less costly jobs result in a lower theoretical bound. Our allocation scheme does not depend on the specific design of the trust evaluation component. Therefore, it can be combined with generic trust evaluation algorithms.Item TRANSPARENCY AND TRUST IN JOURNALISM: AN EXAMINATION OF VALUES, PRACTICES AND EFFECTS(2015) Koliska, Michael; Steiner, Linda; Journalism; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Journalism scholars and practitioners have repeatedly argued that transparency is crucial to generate trust in the news media, which, over the years, has faced continues decline in public trust. As news organizations have been encouraged to implement transparency in their daily work, transparency has increasingly gained the status of a professional norm in journalism. However, very little is actually known about how journalists think and apply transparency in their everyday practices or how news organizations in the United States implement transparency. Similarly, normative assumptions about the trust-generating effects of transparency have not been consistently shown to exist. This dissertation examined to what extent journalists at 12 national news outlets embraced transparency on a day-to-day basis and how these news organizations implement transparency online at the news item level. Moreover, this dissertation tested whether existing features of transparency (hyperlinks, editorial explanations, corrections, staff biographies etc.) impact audiences’ trust perception of a news story. The results of the mixed method approach showed that transparency in journalism is far from being a professional norm, which guides journalists’ news production processes. An analysis of 27 in-depth interviews found that journalists rarely consider transparency in their work. Journalists agreed that the notion of transparency has value. They repeatedly suggested that the news outlets they work for utilize transparency as a promotional tool to engage audiences and to appear transparent, rather than significantly disclosing information about the inner workings of their news organization. The results of the content analysis supported this claim as the findings show that the transparency features news organizations currently use provide little information for audiences to learn about how journalism is done. Meanwhile, the results of two experiments indicate that participants may not recognize the intended meanings of the varied transparency features, as participants’ trust perception did not vary across different transparency conditions. The findings of this dissertation suggest that transparency in journalism is still a goal rather than reality. News organizations have not opened up to the extent that they may be understood as transparent organizations; instead their efforts to pull back the curtain so that audiences may see the inner workings of newsrooms can be considered translucent at best.Item ESSEYS ON HISTORY, CULTURE AND ECONOMIC OUTCOMES(2014) Jancec, MATIJA; Murrell, Peter; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the last decade, there has been a newfound interest within economics in culture, its effects on economic outcomes, and its historical determinants. Although significant progress has been made, there are still many large questions that remain unanswered. My dissertation addresses two of those, namely the effect of history on current levels of trust in political institutions and the twofold relationship between culture and economic outcomes. My first chapter examines the effect of historical changes in political borders on current citizens' levels of trust in political institutions. Political trust also depends on current political institutions, so that a straightforward cross-country analysis would not be able to disentangle the effect of history from the effect of institutions. To address this problem, I compare regions that are part of the same country today and therefore share the same political institutions, but have had a different number of border changes in the past. I study six countries that have such within-country variation in border changes--Slovenia, Croatia, Serbia, Montenegro, Romania and Ukraine. Using data for five hundred years of border changes and three contemporary household-level surveys, I show that more frequent border changes in the past lead to lower current trust in political institutions. The estimated effect is large: border changes can explain 45% of the observed average difference in household-level political trust between the countries studied in my paper and the UK, which has enjoyed stable borders. The second chapter examines immigrants' socio-economic outcomes. I use the variation in cultural distance between immigrants' birth and host countries to estimate the cost of adapting to a new cultural milieu. Using individual level data on immigrants from Europe, Canada and the US, I find that a increase of one standard deviation in the cultural distance between an immigrant's birth and host countries decreases the immigrant's expected earnings by 7.2% and has negative effect on numerous immigrants' social outcomes as well. As predicted by my model, the effect of cultural distance is the strongest for immigrants who arrived recently, and who immigrated at an older age.Item Relational Dynamics in Teacher Professional Development(2013) Finkelstein, Carla; Valli, Linda R; Curriculum and Instruction; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Teacher professional development (PD) is considered essential to improving student achievement toward high standards. I argue that while current notions of high quality PD foreground cognitive aspects of learning, they undertheorize the influence of relational dynamics in teacher learning interactions. That is, current conceptions of high quality PD may be necessary but insufficient to engender teacher learning, and attention to relational dynamics may be essential to leveraging teachers' engagement and productive participation in learning opportunities. A review of the literature from related fields provides preliminary recommendations for addressing affective concerns and relational dynamics in learning, but extrapolation of these recommendations for PD is problematized by particular considerations of teachers as learners, including bureaucratic presses and hierarchical school contexts. A conceptual framework that incorporates power/knowledge considerations may allow for investigation of relational dynamics in PD interactions in a way that takes into account the participants' individual characteristics as well as institutional context. This study uses discourse analysis to examine interactions between three focal teachers and their PD facilitators in a science learning progressions project and a literacy coaching cycle. Examining moments of tension or questions raised by the focal teachers, my analysis finds that close attention to both verbal and nonverbal discourse moves in PD interactions illuminates the ways in which relational dynamics were consequential to the teachers' participation and can help explain the progress or lack of progress for each teacher.Item Security, trust and cooperation in wireless sensor networks(2011) Zheng, Shanshan; Baras, John S.; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Wireless sensor networks are a promising technology for many real-world applications such as critical infrastructure monitoring, scientific data gathering, smart buildings, etc.. However, given the typically unattended and potentially unsecured operation environment, there has been an increased number of security threats to sensor networks. In addition, sensor networks have very constrained resources, such as limited energy, memory, computational power, and communication bandwidth. These unique challenges call for new security mechanisms and algorithms. In this dissertation, we propose novel algorithms and models to address some important and challenging security problems in wireless sensor networks. The first part of the dissertation focuses on data trust in sensor networks. Since sensor networks are mainly deployed to monitor events and report data, the quality of received data must be ensured in order to make meaningful inferences from sensor data. We first study a false data injection attack in the distributed state estimation problem and propose a distributed Bayesian detection algorithm, which could maintain correct estimation results when less than one half of the sensors are compromised. To deal with the situation where more than one half of the sensors may be compromised, we introduce a special class of sensor nodes called \textit{trusted cores}. We then design a secure distributed trust aggregation algorithm that can utilize the trusted cores to improve network robustness. We show that as long as there exist some paths that can connect each regular node to one of these trusted cores, the network can not be subverted by attackers. The second part of the dissertation focuses on sensor network monitoring and anomaly detection. A sensor network may suffer from system failures due to loss of links and nodes, or malicious intrusions. Therefore, it is critical to continuously monitor the overall state of the network and locate performance anomalies. The network monitoring and probe selection problem is formulated as a budgeted coverage problem and a Markov decision process. Efficient probing strategies are designed to achieve a flexible tradeoff between inference accuracy and probing overhead. Based on the probing results on traffic measurements, anomaly detection can be conducted. To capture the highly dynamic network traffic, we develop a detection scheme based on multi-scale analysis of the traffic using wavelet transforms and hidden Markov models. The performance of the probing strategy and of the detection scheme are extensively evaluated in malicious scenarios using the NS-2 network simulator. Lastly, to better understand the role of trust in sensor networks, a game theoretic model is formulated to mathematically analyze the relation between trust and cooperation. Given the trust relations, the interactions among nodes are modeled as a network game on a trust-weighted graph. We then propose an efficient heuristic method that explores network heterogeneity to improve Nash equilibrium efficiency.