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Self-efficacy, Academic Engagement, and Student-teacher Relationships for Ninth-grade African American Male Students’ Algebra I Achievement: a Structural Equation Model

Description: The purpose of the current study was to discern the effects of three latent constructs – self-efficacy, academic engagement, and student-teacher relationships on Algebra I achievement among ninth-grade African American male students. A nationally representative sample from the High School Longitudinal Study of 2009 (HSLS09) was used in the study. Study participants were 697 African American males enrolled in ninth grade in the fall of 2009 across the United States. Structural Equation Modeling (SEM) analytical procedures were performed to test the hypothesized relationships of Bandura’s social cognitive theory (SCT) theoretical assumptions. The results indicate that the three latent variables directly or indirectly were related to Algebra I achievement among ninth grade African American male students. Moreover, the results revealed that self-efficacy and student-teacher relationships constructs had direct significant impact on Algebra I academic performance; nonetheless, the relationships were not strong. These two latent variables had small effect sizes of 5% and 1%, respectively. Combined, self-efficacy, academic engagement, and student-teacher relationships explained only 8% of the variance in the Algebra I achievement among African American males across the United States (R2=.08). The magnitude effect of these factors on Algebra I achievement was minimal. Overall, these findings suggest that the self-efficacy and student-teacher relationships latent variables had a negligible effect as predictors of Algebra I academic success among ninth grade African American male students. A summary of the results are presented and future research is recommended.
Date: December 2015
Creator: Onsongo, Evans N.
Partner: UNT Libraries

Direct and Indirect Effects of Parenting Style with Child Temperament, Parent-Child Relationship, and Family Functioning on Child Social Competence in the Chinese Culture: Testing the Latent Models

Description: Interactional and contextual models have been conceptually proposed in understanding parental influences on children. Yet, empirical model testing has been limited. The purpose of this exploratory study was to investigate the direct and indirect effects of parenting style on child social competence using structural equation modeling in a sample of 544 Chinese families with 6-9 years old children, mainly singleton, residing in Nanjing, China. Five latent models were tested: (a) the direct model between parenting style and child social competence, (b) child temperament as a moderator, (c) parent-child relationship as a mediator, (d) the interaction model between parenting style and family functioning, and (e) bidirectional models of parenting style concurrently with parent-child relationship, and family functioning predicting child social competence. Findings showed: (a) The direct relationship between parenting style and child social competence was significant in both parents with authoritative parenting style on the positive direction, whereas authoritarian and permissive parenting styles on the negative direction; (b) child temperament did not moderate parenting style on child social competence; (c) father-child relationship mediated paternal parenting style on child social competence, whereas maternal parenting style did not; (d) family functioning neither moderated nor mediated the relationship between parenting style and child social competence for both parents; and (e) The four-factor prediction models on child social competence turned out to be unidirectional. For the mothers, the best model was from family functioning to mother-child relationship, to maternal parenting style, and finally to child social competence. Maternal parenting style was the significant proximal factor. For the fathers, it was from family functioning to paternal parenting style, to father-child relationship, and then to child social competence. Father-child relationship had the direct impact, whereas the influence of paternal parenting style was distal through father-child relationship. Findings from this study suggest that the Chinese parents should use ...
Date: May 2007
Creator: Xu, Changkuan
Partner: UNT Libraries

The Information Behavior of Individual Investors in Saudi Arabia

Description: Information plays a significant role in the success of investment strategies. Within a non-advisory context, individual investors elect to build and manage their investment portfolios to avoid the cost of hiring professional advisors. To cope with markets’ uncertainty, individual investors should acquire, understand, and use only relevant information, but that task can be affected by many factors, such as domain knowledge, cognitive and emotional biases, information overload, sources’ credibility, communication channels’ accuracy, and economic costs. Despite an increased interest in examining the financial performance of individual investors in Saudi Arabia, there has been no empirical research of the information behavior of individual investors, or the behavioral biases affecting the investment decision making process in the Saudi stock market (SSM). The purpose of this study was to examine this information behavior within a non-advisory contextualization of their investment decision-making process through the use of an online questionnaire instrument using close-ended questions. The significant intervening variables identified in this study influence the individual investors’ information behavior across many stages of the decision making process. While controlling for gender, education, and income, the optimal information behavior of individual investors in the SSM showed that the Experience factor had the greatest negative effect on the Information Seeking Behavior of individual investors. This was followed by Risk Tolerance, Financial Self-Efficacy, Emotional Biases, Education Level, Formal Information Access, Regret Aversion Bias, and Subjective Financial Knowledge. The Information Acquisition and Information Searching Behavior was influenced by the Acquisition Skepticism, Regret Aversion Bias, Formal Information Access, Overconfidence, and Information Seeking Behavior. Furthermore, the findings indicate that Formal Information Sources have a statistically significant positive effect on the Information Seeking Behavior, and on the Information Acquisition and Information Searching of individual investors in Saudi Arabia. Finally, the Socioeconomic Status (SES) of individual investors in Saudi Arabia was significantly influenced ...
Date: May 2016
Creator: Elwani, Nabil
Partner: UNT Libraries

Convergence of Self and Other Ratings of Personality: a Structural Equation Analysis

Description: Recently, multi-source feedback has been a popular way of providing performance-related feedback to individuals in many organizations. Many who use multi-source feedback consider Rating Convergence, others seeing target individuals as they see themselves, to be a positive outcome of this process. However, the variables that account for Rating Convergence are not known. This study investigated whether the personality factor Extroversion and Behavioral Consistency, acting as a moderator variable, could account for Self-other Rating Convergence, particularly the Convergence between self and peer Ratings. The sample consisted of 235 mid-level managers from a variety of industries who were participants in individual career development workshops. Using structural equation modeling, the results indicated that a model consisting of a single Extroversion factor could account for the convergence of self-peer ratings. This finding calls into question the significance of Rating Convergence when using multi-source rating instruments that provide feedback on trait characteristics since it may be heavily influenced by a single personality factor rather than observers' comprehensive understanding of the ratee's performance.
Date: May 1998
Creator: McElhenie, Michael K. (Michael Keith)
Partner: UNT Libraries

A Structural Equation Model of Contributing Factors to Adolescent Social Interest

Description: The focus of the present study was to test through SEM the relationships between family influences (FI) and school influences (SI) on factors hypothesized to be associated with adolescent social interest: school belonging (SB), extracurricular participation (EP), and peer/romantic involvement (PRI). The final model consisted of FI and SI that contributed to the expression of adolescent social interest. FI included parental communication and parental caring. SI consisted of teacher fairness. SB consisted of a child's self-reported feelings of belonging at school, EP included self-reported involvement in sports or academic clubs, and PRI consisted of self-reported desire for romantic involvement or desire for participation with others. The proposed model suggested that FI contributed significantly to self-reported SB, EP, and PRI. Additionally, it was hypothesized that SI would contribute significantly to SB and EP, but not to PRI. The data used in the current study were part of an existing data set collected as part of the National Longitudinal Study on Adolescent Health. The total sample size for the present study was 2,561 male and female adolescents aged 12-19 years. The data consisted of adolescent and parent self-report information. Results suggested a significant relationship between FI and self-reported SB and PRI. As expected, a significant relationship existed between SI and SB. Also as expected, no significant relationship existed between SI and PRI. Neither the relationship between FI and EP nor SI and EP were significant. When analyzed separately, a significant relationship existed between SB and PRI; however, no significant relationship was found between SB and EP. Results also indicated several of the fit indices, including the average off-diagonal absolute standardized residual, the comparative fit index (CFI), and the Bentler-Bonett non-normed fit index (BBNFI), were a low to moderate fit. However, the final model was highly skewed and the model chi-square and chi-square ...
Date: August 1999
Creator: Craig, Stephen E.
Partner: UNT Libraries

Structural Equation Model of Variables Associated with Family Functioning among a Nationally Representative Sample of Families with a Child with Autism

Description: Previous research indicates that stressors experienced by a family, the perceived level of burden assigned by the family to the stressor, and the utilization of resources predict family functioning. The current study utilized a nationally representative sample of families of children with autistic disorder to determine if previously proposed models of family functioning accurately conceptualized family functioning within a representative sample. Structural equation modeling was utilized to test the double ABCX and the linear ACBX models of family functioning. With slight modifications, the double ABCX model was supported, thus indicating that pileup of stressors, perception of burden, and utilization of resources each have unique predictive ability for family functioning, with perception of burden demonstrating the highest amount of predictive ability. Results, implications, and limitations of the study are discussed.
Date: August 2009
Creator: Bezner, Stephanie K.
Partner: UNT Libraries

The Impact of Quality on Customer Behavioral Intentions Based on the Consumer Decision Making Process As Applied in E-commerce

Description: Perceived quality in the context of e-commerce was defined and examined in numerous studies, but, to date, there are no consistent definitions and measurement scales. Instruments that measure quality in e-commerce industries primarily focus on website quality or service quality during the transaction and delivery phases. Even though some scholars have proposed instruments from different perspectives, these scales do not fully evaluate the level of quality perceived by customers during the entire decision-making process. This dissertation purports to provide five main contributions for the e-commerce, service quality, and decision science literature: (1) development of a comprehensive instrument to measure how online customers perceive the quality of the shopping channel, website, transaction and recovery based on the customer decision making process; (2) identification of the determinants of customer satisfaction and the key dimensions of customer behavioral intentions in e-commerce; (3) examination of the relationships among perceived quality, customer satisfaction and loyalty intention using empirical data; (4) application of different statistical packages (LISREL and PLS-Graph) for data analysis and comparison of how these methods impact the results; and (5) examination of the moderating effects of control variables. A survey was designed and distributed to a total of 1126 college students in a large southwestern university in the U.S. Exploratory factor analysis, confirmatory factor analysis, and structural equation modeling with both LISREL and PLS-Graph are used to validate the comprehensive instrument and test the research hypotheses. The results provide theoretical and normative guidelines for researchers and practitioners in the e-commerce domain. The research results will also help e-commerce platform providers or e-retailers to improve their business and marketing strategies by providing a better understanding of the most important factors influencing customer behavioral intentions.
Date: August 2012
Creator: Wen, Chao
Partner: UNT Libraries

The Effects of Family Cultural Capital on Reading Motivation and Reading Behavior in Elementary School Students with New Immigrant Background: A Structural Equation Model

Description: This study was designed to investigate the impact of family cultural capital on reading motivation and reading behavior among new immigrant children and non-immigrant children. This research used Chang and Wang's family cultural capital, reading motivation, and reading behavior questionnaire to conduct the survey. The target population of this study was students enrolled in fifth grade and sixth grade in elementary school in the fall of 2017 in Tainan, Taiwan. The sample include 414 students from new immigrant families and 422 students from non-immigrant families; the total number of individuals was 837. Structural equation modeling (SEM) analytical procedures were performed to test the hypothesized relationships. The results indicate that the seven latent variables were related to each other directly or indirectly. The main findings of this study are as follows: 1) family socioeconomic status significantly affects students' acquisition of family cultural capital; 2) family reading habits significantly affect students' reading motivation; 3) intrinsic reading motivation significantly affects students' reading behavior; and 4) external reading motivation shows no direct significant effect on reading time or the number of items read.
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Date: August 2018
Creator: Tseng, Hui Te Li
Partner: UNT Libraries

How Exposure to Parental Intimate Partner Violence Affects College Students' Dating Violence: A Structural Equation Model with Adult Attachment and Social Information Processing as Mediating Factors

Description: The effects of childhood exposure to parental intimate partner violence (EPIPV) on dating violence (DV) were examined through two layers of mediations. Based on attachment theory, individuals who are exposed to parental intimate partner violence are less likely to experience secure parent-child attachment, which in turn transfers to insecure adult attachment that is prone to perceive significant others as less trustworthy and less reliable as well as higher likelihood of over-reacting and/or staying in an unhealthy relationship. In the second layer of mediation, insecure adult attachment would lead to biased SIP which in turn, would result in an increase of DV. A total of 327 university students participated in the study by voluntarily completing the research questionnaires. Among them, 253 reported having experienced mild to severe DV and were included in the final data set. The data analyses procedures included examinations of the measurement models and structural equation modeling (SEM) analyses. Findings from the final models best supported by the data indicated that EPIPV predicted both dating violence perpetration and victimization and that EPIPV predicted adult attachment anxiety and avoidance, both of which are consistent with existing literature. However, findings revealed that EPIPV did not predict SIP and SIP was not predictive of DV perpetration. In addition, neither adult attachment anxiety nor attachment avoidance was predictive of DV perpetration and victimization. For DV victimization SEM model, adult attachment anxiety predicted SIP, however, SIP did not predict DV victimization. Findings are discussed based on DV literature and attachment theory. Limitations, clinical implications, and future research directions are also outlined.
Date: August 2017
Creator: Chong, Chu Chian
Partner: UNT Libraries

A Structural Equation Analysis of Intergenerational Differences in Attitudes toward Individual Modernity in the United Arab Emirates: Implications for Cross-Cultural Research

Description: It has been widely believed that modernity is a byproduct of a nuclear family system, a highly urbanized society, and a secular way of life. As such, developing countries are characterized as modern insofar as their social and cultural structures are able to correspond to these criteria. To examine the validity of these propositions, data on two randomly-selected generations--daughters and mothers in the United Arab Emirates--were generated.
Date: May 1997
Creator: Al-Ghazy, Faris M.
Partner: UNT Libraries

Devaluing Stigma in the Context of Forgiveness, Coping and Adaptation: a Structural Regression Model of Reappraisal

Description: The 2010 National HIV/AIDS Strategy outlined three important goals for managing the current HIV pandemic in the U.S.: (1) reduce the number of people who become infected with HIV; (2) improve access to health care and health-related outcomes for people living with HIV/AIDS (PLH/A); and (3) reduce HIV-related health disparities. Each of these goals tacitly depends upon reducing HIV-related stigma, and this study examined how HIV+ individuals evaluate coping efforts to overcome stigma’s impact on quality of life (QOL). a structural regression model was developed to instantiate the reappraisal process described by Lazarus and Folkman’s transactional theory of stress and coping, and this model indicated that maladaptive coping fully mediated the relationship between dispositional forgiveness and perceived stigma, which supports the prediction that coping efficacy is related to stress reduction. Additionally, maladaptive coping fully mediated the relationship between dispositional forgiveness and QOL, supporting the contention that forgiveness is a critical aspect to the evaluative process that influences how PLH/A cope with stigma. Lastly, the model showed that when PLH/A engaged in maladaptive coping to mitigate stress-related stigma, these individuals experienced increased stigmatization and reported significantly lower levels of health-related QOL. in contrast, PLH/A that reported higher levels of dispositional forgiveness were significantly less likely to use maladaptive coping to overcome stigma. Therefore, dispositional forgiveness works through coping to alter perceptions regarding stigmatization, while indirectly influencing attitudes related to health distress, mental health, and cognitive and social functioning. the theoretical and clinical implications of these findings are discussed.
Date: May 2012
Creator: Gates, Michael S.
Partner: UNT Libraries

Integrated Computational and Experimental Approach to Control Physical Texture During Laser Machining of Structural Ceramics

Description: The high energy lasers are emerging as an innovative material processing tool to effectively fabricate complex shapes on the hard and brittle structural ceramics, which previously had been near impossible to be machined effectively using various conventional machining techniques. In addition, the in-situ measurement of the thermo-physical properties in the severe laser machining conditions (high temperature, short time duration, and small interaction volume) is an extremely difficult task. As a consequence, it is extremely challenging to investigate the evolution of surface topography through experimental analyses. To address this issue, an integrated experimental and computational (multistep and multiphysics based finite-element modeling) approach was employed to understand the influence of laser processing parameters to effectively control the various thermo-physical effects (recoil pressure, Marangoni convection, and surface tension) during transient physical processes (melting, vaporization) for controlled surface topography (surface finish). The results indicated that the material lost due to evaporation causes an increase in crater depth of machined cavity, whereas liquid expulsion created by the recoil pressure increases the material pileup height around the lip of machined cavity, the major attributes of surface topography (roughness). Also, it was found that the surface roughness increased with increase in laser energy density and pulse rate (from 10 to 50Hz), and with the decrease in distance between two pulses (from 0.6 to 0.1mm) or the increase in lateral and transverse overlap (0, 17, 33, 50, 67, and 83%). The results of the computational model are also validated by experimental observations with reasonably close agreement.
Date: December 2013
Creator: Vora, Hitesh D.
Partner: UNT Libraries

Computational Modeling of Small Molecules

Description: Computational chemistry lies at the intersection of chemistry, physics, mathematics, and computer science, and can be used to explain the behavior of atoms and molecules, as well as to augment experiment. In this work, computational chemistry methods are used to predict structural and energetic properties of small molecules, i.e. molecules with less than 60 atoms. Different aspects of computational chemistry are examined in this work. The importance of examining the converged orbitals obtained in an electronic structure calculation is explained. The ability to more completely describe the orbital space through the extrapolation of energies obtained at increasing quality of basis set is investigated with the use of the Sapporo-nZP-2012 family of basis set. The correlation consistent Composite Approach (ccCA) is utilized to compute the enthalpies of formation of a set of molecules and the accuracy is compared with the target method, CCSD(T,FC1)/aug-cc-pCV∞Z-DK. Both methodologies are able to produce computed enthalpies of formation that are typically within 1 kcal mol-1 of reliable experiment. This demonstrates that ccCA can be used instead of much more computationally intensive methods (in terms of memory, processors, and time required for a calculation) with the expectation of similar accuracy yet at a reduced computational cost. The enthalpies of formation for systems containing s-block elements have been computed using the multireference variant of ccCA (MR-ccCA), which is designed specifically for systems that require an explicit treatment of nondynamical correlation. Density functional theory (DFT) has been used for the prediction of the structural properties of a set of lanthanide trihalide molecules as well as the reaction energetics for the rearrangement of diphosphine ligands around a triosmium cluster.
Date: December 2015
Creator: Weber, Rebecca J.
Partner: UNT Libraries

Fractional Integration and Political Modeling

Description: This dissertation investigates the consequences of fractional dynamics for political modeling. Using Monte Carlo analyses, Chapters II and III investigate the threats to statistical inference posed by including fractionally integrated variables in bivariate and multivariate regressions. Fractional differencing is the most appropriate tool to guard against spurious regressions and other threats to inference. Using fractional differencing, multivariate models of British politics are developed in Chapter IV to compare competing theories regarding which subjective measure of economic evaluations best predicts support levels for the governing party; egocentric measures outperform sociotropic measures. The concept of fractional cointegration is discussed and the value of fractionally integrated error correction mechanisms are both discussed and demonstrated in models of Conservative party support. In Chapter V models of presidential approval in the United States are reconfigured in light of the possibilities of fractionally integrated variables. In both the British and American case accounting for the fractional character of all variables allows the development of more accurate multivariate models.
Date: August 1999
Creator: Lebo, Matthew Jonathan
Partner: UNT Libraries

Improvement of the Soil Moisture Diagnostic Equation for Estimating Root-Zone Soil Moisture

Description: Soil moisture information can be used accurately in determining the timing and amount of irrigation applied to plants. Pan and Pan et al. proposed a robust and simple daily diagnostic equation for estimating daily soil moisture. The diagnostic equation evaluates the relationship between the soil moisture loss function and the summation weighted average of precipitation. The loss function uses the sinusoidal wave function which employs day of the year (DOY) to evaluate the seasonal variation in soil moisture loss for a given year. This was incorporated into the daily diagnostic equation to estimate the daily soil moisture for a location. Solar radiation is an energy source that drives the energy and water exchanges between vegetation and the atmosphere (i.e., evapotranspiration), and thus impacts the soil moisture dry-down. In this paper, two parameters (the actual solar radiation and the clear sky solar radiation) are introduced into loss function coefficient to improve the estimation of soil moisture. After the Introduction of the solar radiation data into soil moisture loss function, a slight improvement was observed in the estimated daily soil moisture. Pan observed that generally the correlation coefficient between the estimated and the observed soil moisture is above 0.75 and the root mean square error is below 5.0 (%v/v). The introduction solar radiation data (i.e. clear sky solar radiation and actual solar) improve the correlation coefficient average for all the sites evaluated by 0.03 when the root mean square error is generally below 4.5(%v/v) for the entire root zone.
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Date: May 2018
Creator: Omotere, Olumide Olubunmi
Partner: UNT Libraries

Modeling Utilization of Planned Information Technology

Description: Implementations of information technology solutions to address specific information problems are only successful when the technology is utilized. The antecedents of technology use involve user, system, task and organization characteristics as well as externalities which can affect all of these entities. However, measurement of the interaction effects between these entities can act as a proxy for individual attribute values. A model is proposed which based upon evaluation of these interaction effects can predict technology utilization. This model was tested with systems being implemented at a pediatric health care facility. Results from this study provide insight into the relationship between the antecedents of technology utilization. Specifically, task time provided significant direct causal effects on utilization. Indirect causal effects were identified in task value and perceived utility constructs. Perceived utility, along with organizational support also provided direct causal effects on user satisfaction. Task value also impacted user satisfaction in an indirect fashion. Also, results provide a predictive model and taxonomy of variables which can be applied to predict or manipulate the likelihood of utilization for planned technology.
Date: May 2000
Creator: Stettheimer, Timothy Dwight
Partner: UNT Libraries

Predictive Modeling for Persuasive Ambient Technology

Description: Computer scientists are increasingly aware of the power of ubiquitous computing systems that can display information in and about the user's environment. One sub category of ubiquitous computing is persuasive ambient information systems that involve an informative display transitioning between the periphery and center of attention. The goal of this ambient technology is to produce a behavior change, implying that a display must be informative, unobtrusive, and persuasive. While a significant body of research exists on ambient technology, previous research has not fully explored the different measures to identify behavior change, evaluation techniques for linking design characteristics to visual effectiveness, nor the use of short-term goals to affect long-term behavior change. This study uses the unique context of noise-induced hearing loss (NIHL) among collegiate musicians to explore these issues through developing the MIHL Reduction Feedback System that collects real-time data, translates it into visuals for music classrooms, provides predictive outcomes for goalsetting persuasion, and provides statistical measures of behavior change.
Date: August 2015
Creator: Powell, Jason W.
Partner: UNT Libraries

The Effects of Neighboring, Social Networks, and Collective Efficacy on Crime Victimization: an Alternative to the Systemic Model

Description: The systemic model posits that informal social control directly reduces crime victimization and social networks indirectly reduce crime victimization through informal social control. While empirical testing of the systemic model advanced the theory, important analytical issues remain. First, social networks are inconsistently conceptualized and measured. Second, the conceptual relationship between social networks and informal social control remains unclear. This study addresses these issues by testing an alternative to the systemic model, including new constructs and hypotheses. The goal is to develop better indicators for the model and refine the theory, rethinking and deepening the existing theory about neighborhood effects on crime victimization. The data come from the 2002-2003 Seattle Neighborhoods and Crime Survey (N=2,200). Structural equation modeling (SEM), a multivariate statistical technique, was used to analyze these data. The SEM included five latent constructs (neighboring, neighborhood and non-neighborhood social networks, collective efficacy, and crime victimization) and six social structural variables (racially homogeneous neighborhood, resident tenure, household income, family disruption, male, and non-white ethnicity). One of my 9 hypotheses was supported; the remaining hypotheses were partly supported. The results support my argument that the systemic model is too simplistic, but the relationships among the variables are not exactly as I hypothesized. The results provide insight into the complexities of the systemic model and areas for future research.
Date: May 2015
Creator: Soto, Anthony Jaime
Partner: UNT Libraries

Dislocation Dynamics Simulations of Plasticity in Cu Thin Films

Description: Strong size effects in plastic deformation of thin films have been experimentally observed, indicating non-traditional deformation mechanisms. These observations require improved understanding of the behavior of dislocation in small size materials, as they are the primary plastic deformation carrier. Dislocation dynamics (DD) is a computational method that is capable of directly simulating the motion and interaction of dislocations in crystalline materials. This provides a convenient approach to study micro plasticity in thin films. While two-dimensional dislocation dynamics simulation in thin film proved that the size effect fits Hall-Petch equation very well, there are issues related to three-dimensional size effects. In this work, three-dimensional dislocation dynamics simulations are used to study model cooper thin film deformation. Grain boundary is modeled as impenetrable obstacle to dislocation motion in this work. Both tension and cyclic loadings are applied and a wide range of size and geometry of thin films are studied. The results not only compare well with experimentally observed size effects on thin film strength, but also provide many details on dislocation processes in thin films, which could greatly help formulate new mechanisms of dislocation-based plasticity.
Date: August 2013
Creator: Wu, Han
Partner: UNT Libraries

Comparing Three Approaches for Handling a Fourth Level of Nesting Structure in Cluster-Randomized Trials

Description: This study compared 3 approaches for handling a fourth level of nesting structure when analyzing data from a cluster-randomized trial (CRT). CRTs can include 3 levels of nesting: repeated measures, individual, and cluster levels. However, above the cluster level, there may sometimes be an additional potentially important fourth level of nesting (e.g., schools, districts, etc., depending on the design) that is typically ignored in CRT data analysis. The current study examined the impact of ignoring this fourth level, accounting for it using a model-based approach, and accounting it using a design-based approach on parameter and standard error (SE) estimates. Several fixed effect and random effect variance parameters and SEs were biased across all 3 models. In the 4-level model, most SE biases decreased as the number of level 3 clusters increased and as the number of level 4 clusters decreased. Also, random effect variance biases decreased as the number of level 3 clusters increased. In the 3-level and complex models, SEs became more biased as the weight level 4 carried increased (i.e., larger intraclass correlation, more clusters at that level). The current results suggest that if a meaningful fourth level of nesting exists, future researchers should account for it using design-based approach; the model-based approach is not recommended. If the fourth level is not practically important, researchers may ignore it altogether.
Date: August 2017
Creator: Glaman, Ryan
Partner: UNT Libraries

An Empirical Investigation of the Structural Form and Measurement Validity of the Hill Inventory

Description: This research began with the Hill Inventory. Cognitive style preference variables were classified as one of following four types: Theoretical Codes, Qualitative Codes, Social-Cultural Codes or Reasoning Modalities. A consumer behavior perspective was then used to form an alternative structure for the Hill Inventory variables. The following three constructs were proposed: Evaluation Codes, Perceptual Codes, and Reasoning Modalities. The purpose of this research was to assess the structural form and measurement validity of the Hill Inventory. Specific steps taken to accomplish this objective included: developing confirmatory factor and structural equation models; using the LISREL software package to analyze the model specifications; and assessing the validity of the questions used to measure the variables. A descriptive research design was used to compare the model specifications. The research instrument consisted of eight statements for each of twenty-eight variables for a total of 224 questions. Five-point response choices were described by the words: often, sometimes, unsure, rarely, or never. The sample consisted of 285 student subjects in marketing classes at a large university. Data analysis began by comparing the distributions of the data to a normal case. Parameter estimates, root mean square residuals and squared multiple correlations then were obtained using the LISREL VI software package. The chi-square statistic was used to test the hypotheses. This statistic was supplemented by the Tucker-Lewis index which used a null model for comparisons. The final step in data analysis was to assess the reliability of the measurements. This study affected the potential usage of the Hill Inventory for consumer behavior research. The major conclusion was that the measurement of the variables must be improved before model parameters can be tested. Specific question sets on the inventory were identified that were most in need of revision.
Date: August 1988
Creator: Blake, Faye W.
Partner: UNT Libraries

Modeling Infectious Disease Spread Using Global Stochastic Field Simulation

Description: Susceptibles-infectives-removals (SIR) and its derivatives are the classic mathematical models for the study of infectious diseases in epidemiology. In order to model and simulate epidemics of an infectious disease, a global stochastic field simulation paradigm (GSFS) is proposed, which incorporates geographic and demographic based interactions. The interaction measure between regions is a function of population density and geographical distance, and has been extended to include demographic and migratory constraints. The progression of diseases using GSFS is analyzed, and similar behavior to the SIR model is exhibited by GSFS, using the geographic information systems (GIS) gravity model for interactions. The limitations of the SIR and similar models of homogeneous population with uniform mixing are addressed by the GSFS model. The GSFS model is oriented to heterogeneous population, and can incorporate interactions based on geography, demography, environment and migration patterns. The progression of diseases can be modeled at higher levels of fidelity using the GSFS model, and facilitates optimal deployment of public health resources for prevention, control and surveillance of infectious diseases.
Date: August 2006
Creator: Venkatachalam, Sangeeta
Partner: UNT Libraries

Structural, Thermal and Acoustic Performance of Polyurethane Foams for Green Buildings

Description: Decreasing the carbon footprint through use of renewable materials has environmental and societal impact. Foams are a valuable constituent in buildings by themselves or as a core in sandwich composites. Kenaf is a Southeast USA plant that provides renewable filler. The core of the kenaf is porous with a cell size in a 5-10 micrometer range. The use of kenaf core in foams represents a novel multiscalar cellular structural composite. Rigid polyurethane foams were made using free foaming expansion with kenaf core as filler with loadings of 5, 10 and 15 %. Free foaming was found to negatively affect the mechanical properties. An innovative process was developed to introduce a constraint to expansion during foaming. Two expansion ratios were examined: 40 and 60 % (decreasing expansion ratio). MicroCT and SEM analysis showed a varying structure of open and closed cell pores. The mechanical, thermal insulation, acoustic properties were measured. Pure PU foam showed improved cell size uniformity. Introducing kenaf core resulted in decreasing the PU performance in the free expansion case. This was reversed by introducing constraints. To understand the combined impact of having a mixed close cell and open cell architecture, finite element modeling was done using ANSYS. Models were created with varying percentages of open, closed, and bulk cells to encompass entire range of foam porosities. Net zero energy building information modelling was conducted using EnergyPlus was conducted using natural fiber composite skins. Environmental impacts for instance global warming potential, acidification, eutrophication, fossil fuel consumption, ozone depletion, and smog potential of the materials used in construction was studied using life cycle assessment. The results showed improvement on energy consumption and carbon footprint.
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Date: December 2014
Creator: Nar, Mangesh
Partner: UNT Libraries