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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Estimating Multilevel Structural Equation Models with Random Slopes for Latent Covariates

Rockwood, Nicholas John 03 July 2019 (has links)
No description available.
122

Abuse Severity, Family Environment, and Caregiver Distress as Predictors of Adjustment Among Sexually Abused Youth

Stewart, Lindsay McKenna 01 January 2010 (has links)
Much of the research on childhood sexual abuse (CSA) has utilized demographic factors (e.g., the gender, age, and race/ethnicity of the child victim) and specific characteristics of the abusive experience (e.g., the severity of abuse, the relationship between the perpetrator and the child victim, the child's age at the onset of abuse, etc.) as predictors of children's adjustment. Unfortunately, the ability of such factors to predict children's adjustment consistently across studies has been limited. Alternatively, while it has been recognized that survivors of CSA often hail from dysfunctional family environments and that the disclosure of CSA frequently results in emotional distress for caregivers, less research has focused on how these factors may serve to influence sexually abused children's adjustment. This study included 163 sexually abused youth and their non-offending caregivers who completed measures of psychological adjustment and the family environment. Demographic information and abuse-related characteristics were also collected. Children's age, gender, and race/ethnicity were not significantly predictive of emotional adjustment. Structural equation modeling was used to examine the direct and indirect effects of total abuse severity, caregiver distress, and children's perceptions of their family environments as predictors of emotional adjustment. Results indicated that both children's perceptions of their family environments and total abuse severity were significantly predictive of children's emotional adjustment, whereas caregiver distress did not have significant direct or indirect effect on adjustment. Finally, the implications of these findings for future research and the development of effective interventions for sexually abused children and their families was discussed
123

The role of transformational leadership in influencing students' outcomes in public secondary schools in Kuwait

Alfraih, Fraih January 2014 (has links)
This study investigates the role of transformational leadership in influencing students’ outcomes in public secondary schools using Kuwait as a case study. The standard of academic achievement in Kuwait’s public schools has been declining over the years, which calls for a different type of leadership to transform these schools. It is argued in this thesis that there is merit in bringing in private sector business models to the public education sector in order to transform the sector and improve the schools’ outcomes. Furthermore, not much research has been undertaken on the paths through which transformational leadership influences public school outcomes in developing countries such as Kuwait. Following a critical review of leadership literature, a theoretical model for leadership that is transformational was conceptualised and this formed the basis of hypotheses formation and data collection. The thesis is thus original in its attempt to understand the paths through which school heads’ transformational leadership influence student’s outcomes in public secondary schools in a developing country (Kuwait). The study adopted a positivist ontology and objective epistemology and obtained data from 495 school heads and staff from 86 public secondary schools in Kuwait via a structured questionnaire. Confirmatory factor analysis (CFA) and structural equation models (SEM) tested the direct and indirect effects of school heads’ transformational leadership in influencing students’ outcomes the student “achievement” and the student “engagement” via several mediating variables including “school culture”, “class room condition” and “academic emphasis”. The analysis identified idealized influence (attributes) and idealized influence (behaviour) as the underlying dimensions of transformational leadership that directly and indirectly influences both student engagement and student achievement as the final outcome. The findings also confirmed differences between males and females in their leadership styles and subsequent influence on students’ achievement, and student engagement with the latter appearing to be better school heads. Therefore, two structure equation models were built to investigate the characteristics of each gender leadership style on the outcome variables. The findings also revealed that males’ leadership style has significant effect on student achievement but not student on engagement, while female leader ship style has significant effect on both student achievement and student engagement stronger than the males’ effect counterpart. Generally however, transformational leadership style has significant effect on both student achievement and student engagement. The study objectives were met and the study contributes to understanding the role of transformational leadership and its influence on staff and students’ achievement, from a developing country in the GCC. Managerial recommendations and suggestions for policy makers are made. Study limitations are highlighted leading to suggestions for further study.
124

Instrumental variable and longitudinal structural equation modelling methods for causal mediation : the PACE trial of treatments for chronic fatigue syndrome

Goldsmith, Kimberley January 2014 (has links)
Background: Understanding complex psychological treatment mechanisms is important in order to refine and improve treatment. Mechanistic theories can be evaluated using mediation analysis methods. The Pacing, Graded Activity, and Cognitive Behaviour Therapy: A Randomised Evaluation (PACE) trial studied complex therapies for the treatment of chronic fatigue syndrome. The aim of the project was to study different mediation analysis methods using PACE trial data, and to make trial design recommendations based upon the findings. Methods: PACE trial data were described using summary statistics and correlation analyses. Mediation estimates were derived using: the product of coefficients approach, instrumental variable (IV) methods with randomisation by baseline variables interactions as IVs, and dual process longitudinal structural equation models (SEM). Monte Carlo simulation studies were done to further explore the behaviour of IV estimators and to examine aspects of the SEM. Results: Cognitive and behavioural measures were mediators of the cognitive behavioural and graded exercise therapies in PACE. Results were robust when accounting for correlated measurement error and different SEM structures. Randomisation by baseline IVs were weak, giving imprecise and sometimes extreme estimates, leaving their utility unclear. A flexible version of a latent change SEM with contemporaneous mediation effects and contemporaneous correlated measurement errors was the most appropriate longitudinal model. Conclusions: IV methods using interaction IVs are unlikely to be useful; designs with randomised IV might be more suitable. Longitudinal SEM for mediation in clinical trials seems a promising approach. Mediation estimates from SEM were generally robust when allowing for correlated measurement error and for different model classes. Mediation analysis in trials should be longitudinal and should consider the number and timing of measures at the design stage. Using appropriate methods for studying mediation in trials will help clarify treatment mechanisms of action and allow for their refinement, which would maximize the information gained from trials and benefit patients.
125

Effective Change Management in Modern Enterprises

Karnouskos, Stamatis January 2015 (has links)
Modern enterprises are constantly under change in the effort to enhance their internal operations and become more competitive in the market. A change process is always a challenge, and its success needs to consider multi-angled approaches, as it affects all involved stakeholders. The way changes are tack- led is fundamental to the success and survivability of an enterprise. Change is interwoven with risks, and therefore it has to be effectively managed in order to be successful. This work presents an effort to identify the key factors that should be con- sidered in order to lead to effective change management in modern enter- prises, and quantify their relationship to it. The theoretical investigation re- veals that key factors often considered, both in theory and in practical change management strategies, include Employee, Leadership, Training & Develop- ment, Reward & Recognition, Culture, Politics, Information Systems. Driven by these findings, a model is proposed that depicts their correlation towards effective change management. Subsequently, a survey is conducted, and sta- tistical analysis is performed to the empirical data collected, in order to eval- uate the proposed model and its hypotheses. The empirical results indicate that all selected key factors, contribute towards achieving effective change management as hypothesized. The results of this work, may benefit enterprise managers planning, exe- cuting and assessing change processes, as proper considerations of the factors discussed throughout this work may increase the chances of the change pro- cess success, resulting in a better performing and competitive enterprise.
126

Race, personal history characteristics, and vocational rehabilitation outcomes : a structural equation modeling approach

Martin, Frank H. 19 October 2009 (has links)
Numerous studies have indicated racial and ethnic disparities in the vocational rehabilitation (VR) system, including differences in eligibility, services provided, and employment outcomes. Few of these studies, however, have utilized advanced multivariate techniques or latent constructs to measure quality of employment outcomes (QEO) or tested hypothesized models for the relationship between race, personal history characteristics, and VR outcomes. Furthermore, few VR disparities studies have examined southwestern states such as Texas, which has large Hispanic and Black populations. The purpose of this study was to utilize structural equation modeling (SEM) to examine several implied conceptual models for the relationship between race, personal history characteristics, and VR outcomes for White, Black, and Hispanic participants in the Texas VR system. The implied conceptual models were tested for goodness of fit and multiple-group invariance. A measurement model for QEO, a latent construct, was tested and used in the study. QEO was measured by three indicator variables and evaluated using confirmatory factor analysis. A MIMIC model was tested to assess racial/ethnic variation in QEO. The MIMIC results were compared to a multiple regression approach. In addition, a path model and logistic regressions were conducted to assess racial variation in VR closure status among consumers who were unemployed at application to VR. All models were retested with an independent sample to assess predictive validity. The study results indicated good model fit and measurement invariance for the QEO construct. The structural model for race, personal history characteristics, and QEO indicated moderate model fit. It also indicated interaction effects for race by gender and for race by public support. The MIMIC model results suggest that QEO decreased for Blacks and Hispanics compared to Whites. Furthermore, the MIMIC results, which utilized QEO as an endogenous variable, differed from the multiple regression findings, which utilized one criterion. The multiple regression findings indicated no statistically significant difference between Blacks and Whites. The path model for race and VR closure status indicated poor model fit. The logistic regression indicated no racial/ethnic differences in VR closure status. Several model estimates did not cross-validate. Study limitations and suggestions for future research are described. / text
127

Modeling the relationships among topical knowledge, anxiety, and integrated speaking test performance: a structural equation modeling approach

Huang, Heng-Tsung Danny 27 September 2010 (has links)
Thus far, few research studies have examined the practice of integrated speaking test tasks in the field of second/foreign language oral assessment. This dissertation utilized structural equation modeling (SEM) and qualitative techniques to explore the relationships among topical knowledge, anxiety, and integrated speaking test performance and to compare the influence of topical knowledge and anxiety, respectively, on independent speaking test performance and integrated speaking test performance. Three instruments were employed in this study. First, three integrated tasks were derived from TOEFL-iBT preparation materials, and three independent tasks were developed specifically for this research study. Second, four topical knowledge tests (TKTs) were constructed by six content experts and validated on a group of 421 Taiwanese EFL learners. Third, the state anxiety inventory (SAI) from the State-Trait Anxiety Inventory was adopted. A total of 352 Taiwanese EFL students were recruited for the official study. At the first stage, they filled out the personal information sheet and responded to the TKTs. At the second stage, they took two independent tasks for which they spoke without input support, responded to an SAI, performed two integrated tasks in which they orally summarized the textual and auditory input given to them, and completed another SAI. Finally, 23 volunteers took part in follow-up interviews. The quantitative data were analyzed using the two-step SEM approach and the interview data were examined using a series of qualitative techniques, leading to five primary findings. First, topical knowledge and anxiety both strongly influenced the integrated speaking performance, though in an opposite manner. Second, topical knowledge did not significantly affect anxiety. Third, the effect of topical knowledge on independent speaking performance and integrated speaking performance varied depending on the topics of the tasks. Fourth, the impact of anxiety on independent speaking performance and integrated speaking performance also differed according to the topics of the tasks. Fifth, participants were overwhelmingly positive about the integrated tasks. In light of the findings, several implications are proposed for second/foreign language oral assessment theory, research methodology, and practice. / text
128

Tree holes as habitat for aquatic and terrestrial invertebrates in mixed broadleaf-podocarp rainforest, New Zealand

Blakely, Tanya Jillaine January 2008 (has links)
Little is known about the spatial distribution and abundance of tree holes in New Zealand’s native forests, or the invertebrate communities that they support. I found that tree holes were common on five endemic tree species, belonging to the families Fagaceae and Podocarpaceae in the mixed broadleaf-podocarp rainforest of Orikaka Ecological Area, Buller District, New Zealand. However, tree holes were not uniformly distributed throughout the forest, with more holes found on the three podocarp species, Prumnopitys ferruginea, P. taxifolia and Dacrycarpus dacrydioides, than on Nothofagus fusca or N. menziesii. Nevertheless, Nothofagus fusca had the largest holes of any of the tree species sampled and larger trees generally had larger holes. Large, hole-bearing Nothofagus fusca trees support a specialist hole-dwelling vertebrate fauna in New Zealand and worldwide, tree holes provide habitat for a range of invertebrate species. Using specially-designed emergence traps, I collected invertebrates emerging from naturally-occurring dry tree holes and compared this assemblage with invertebrates inhabiting leaf litter on the forest floor and those dispersing aerially throughout the study area. At the higher taxonomic resolution (i.e., Order or Class), community composition within the tree holes was highly variable, and there was no strong distinction between invertebrates from tree holes, leaf litter or Malaise traps. Moreover, although some beetle species emerging from tree holes were found exclusively in tree holes, most of these were represented by a single individual. Consequently, only minor differences in species composition were detected between beetle assemblages from tree holes, leaf-litter and those aerially dispersing throughout the forest. In contrast, the aquatic invertebrate assemblage within water-filled tree holes was highly distinctive from that in ground-based freshwater ecosystems, with only six aquatic taxa in common between all freshwater habitats. Using experimental water-filled tree-hole microcosms, I found that species richness and community composition within these microcosms were primarily driven by resource concentration, although habitat quality (i.e., water chemistry parameters) was also an important determinant of the identity and composition of colonising species. Overall, my study has shown that tree holes are common in the study area, and are likely to be more abundant in New Zealand’s indigenous forests than previously thought. Moreover, these generally small, discrete forest ecosystems support a diverse array of terrestrial invertebrates as well as a distinctive aquatic invertebrate community that is primarily structured by organic matter resource availability. These findings not only represent an important advance in our knowledge of New Zealand’s freshwater invertebrate biodiversity, but also highlight the need for further investigation into these unique forest canopy habitats which may well be at risk from deforestation and land use change.
129

Self-Imposed Activity Limitation Among Community Dwelling Elders

Guo, Guifang January 2007 (has links)
This study explored the emerging Self-Imposed Activity Limitation (SIAL) theory among community dwelling elders. This theory was examined using the proposed Aging Well Conceptual model which was guided by Baltes' Selection, Optimization with Compensation model, Markus and Nurius' Envisioned Possible Selves theory, Kuypers and Bengtson's Social Breakdown Syndrome model, Bandura's Self-Efficacy theory, and Rotter's Locus of Control theory. The objectives of this study were to explore the relationships among multiple variables in a hierarchical model and to examine the explanatory power of the SIAL variables in predicting elders' well-being.A correlational descriptive design with a causal modeling approach was used employing Structural Equation Modeling (SEM) techniques. The Aging Well model was tested through a secondary analysis of the National Survey of Midlife Development in the United States (MIDUS) database selecting respondents aged 65-74 years.Two research questions guided this study. Research question one, how well does the Aging Well model fit with empirical sample data, was explored. The Aging Well model statistically approximated the MIDUS data after theoretical and statistical modifications and explained 76% of the variance of elder's well-being. The mediating effects of SIAL variables were determined by nested alternative model testing. Research question two, are the proposition statements in the Aging Well model valid, and was demonstrated empirically by the expected patterns of correlation and covariance among most of the variables in the Aging Well model.SIAL as a composite factor had a large positive effect on elder's well-being. Elders' perceived constraints and perception of aging had no direct effect on well-being. The influences of these two factors on well-being were mediated by a common factor, SIAL. These findings supported the emerging SIAL theory by suggesting that the optimal use of SIAL would lead to adaptive outcomes promoting elders' well-being. In addition, SIAL mediated the effects of elders' sense of control and perception of aging on well-being. The full range of SIAL could not be examined due to limitations inherent in secondary data analysis.
130

Analyzing the use of UTAUT model in explaining an online behaviour : Internet banking adoption

Al-Qeisis, Kholoud Ibrahim January 2009 (has links)
Technology acceptance research is a constantly developing field. The disciplines that contributed to its development are either beliefs focused or system focused. The unified theory of acceptance and use of technology (UTAUT) combined both. The current research model proposes an extension to the UTAUT that accounts for online usage behaviour. The proposed research model is tested in two countries (UK and Jordan) to investigate the viability of the unified model of technology acceptance in different boundaries as a model of individuals’ discretionary usage of Internet banking. The study also questions the roles of other determinants and moderators in this context. Results found support for the effect of the proposed extension, website quality perceptions, on usage behaviour in both countries’ models; the total effect of this extension exhibited website quality perceptions the most influential determinant of usage behaviour in both models and performance expectancy construct was second in effect. Social influence had no impact on the usage behaviour in both models, which is consistent with previous research that advocates a declining role of social influence under discretionary usage and increased experience conditions. Furthermore, the moderating role of performance expectancy previously established in TAM’s research was supported in the UTAUT model in both countries’ models. Moreover, both models reported a non-moderating effect of gender, which, is also in line with recent research findings that suggest declining gender differences under voluntary usage conditions and advanced experience. Education and income were moderators only for the UK model. Although the research findings demonstrated that both countries’ models were “configurally” similar with respect to model specifications, the models’ explanatory power for usage behaviour was dissimilar: the UK’s model explanatory power exceeded that of Jordan’s model presenting an opportunity for future research. The current research contributes to knowledge in the field of technology acceptance research. It demonstrated that website quality perceptions, as a multidimensional concept, play an important role in the online usage context. It also demonstrated that the unified model of technology acceptance established in the western culture can be transferred to a non-western culture although with varying degrees of explanation power.

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