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<p> In this project we used structural equation modeling to analyze the data collected for the Canadian Community Health Survey (CCHS) Cycle 1.2 - Mental Health and Well-Being conducted by Statistics Canada. The data are cross-sectional.</p> <p> We looked at the relation between depression and obesity adjusting for gender, socioeconomic status, gene-environment interactions, eating and physical activity and stress.</p> <p> We used the AMOS and Mplus softwares to analyze our data. The first one used continuous variables for depression ("persistence of depression", in years) and obesity ("body mass index"-BMI), while the second used categorical variables: lifetime depression, 12 month depression and obesity (normal weight, overweight and obese). We also used two variables to measure different aspects of stress: self-perceived ability to handle an unexpected problem and work stress-social support.</p> <p> We fitted the models across the entire data, but also across different groups: males versus females and groups based on gender and BMI.</p> <p> The results indicated that the relationship between depression and obesity is different across gender.</p> <p> The limitations of the study are also discussed. </p> / Thesis / Master of Science (MSc)

High rates of medical errors are well documented within the healthcare industry. Nurses, in particular, play a critical role in the quality and safety of healthcare services. Fatigue is a factor that has been linked to stress, safety, and performance decrements in numerous work environments. Within healthcare, however, a comprehensive definition of fatigue encompassing multiple dimensions has not been considered, but is warranted since nurses perform tasks consisting of diverse physical and mental activities. As such, "total fatigue" was examined, as were interactions between its underlying dimensions and the effects of these dimensions on performance, in the context of actual and simulated nursing work. In a survey study (Chapter 2), registered nurses reported relatively high levels of mental, physical, and total fatigue, and higher levels of fatigue were associated with perceived decreases in performance. Work environment variables, such as work schedule or shift length, were also related to differences in reported fatigue levels. An experimental study investigated causal effects of mental and physical fatigue on mental and physical performance (Chapter 3). Mental fatigue affected a measure of mental performance, and physical fatigue had a negative effect on measures of physical and mental performance. A multidimensional view of fatigue that considers direct and crossover effects between mental and physical dimensions of fatigue and performance is relevant when quantifying effects of fatigue on performance. A model of the relationships between fatigue dimensions and performance in nursing was developed using structural equation modeling techniques (Chapter 4). The model supported the existence of a total fatigue construct that is directly affected by mental and physical fatigue levels. The final model also provides quantitative path coefficients defining the strength of relationships between mental and physical dimensions of fatigue, total fatigue, and mental and physical performance. The current research provides an increased understanding of fatigue levels in registered nurses across work environments, as well as the underlying causal mechanisms between dimensions of fatigue and performance decrements. The findings and the final model can aid in designing interventions to reduce or eliminate the contributions of fatigue to the occurrence of medical errors. / Ph. D.

This study seeks to offer a meaningful statement about the relative importance of self-processes and activated social capital in the process that links high school students and educational outcomes. The conceptual model for the study draws on the large and diverse body of research that aims to understand the process and effects of the interaction of the person and his or her environment. It is hypothesized that adaptive self-processes and social capital are positively related to school engagement, educational aspirations, and actual performance in school; and, that these factors mediate the effects of family background and other potential social capital on educational outcomes. The data for this study were obtained from a sample of N=1,176 in grades 9-12 from three school divisions in Virginia. Students completed the School Relationships and Experiences Survey (SRES), an instrument designed for this study. The study uses structural equation modeling (SEM) to model the relationships between the variables of interest. Data were analyzed using LISREL 8.3 (Jöreskog & Sörbom, 1993). The covariance structure models tested include both single-indicator and multiple-indicator constructs. The analysis follows the two-step procedure suggested by Anderson and Gerbing (1988). First, a measurement model was tested using confirmatory factor analysis to develop a model with acceptable fit to the data. In step two, the theoretical model of interest was specified as an a priori model. This theoretical model was then tested and revised until a theoretically meaningful and statistically acceptable model was found. In conclusion, the results of the analyses are discussed, and possible explanations for the results are proposed. Directions for future research are outlined, including the need for cross-validation of this model on additional samples of high school students. Social capital has previously been conceptualized primarily as family resources and parent-child relationships. This study provides promising initial evidence that activated social capital (education-related support received by adolescents from the broader social network) has stronger and more meaningful effects on academic engagement and other educational outcomes than the more passive indicators of social capital used in previous research. This work was supported by a doctoral fellowship from the Social Sciences and Humanities Research Council of Canada (SSHRC) and a grant from the ASPIRES program at Virginia Tech. / Ph. D.

Although anxiety disorders and conduct problems often co-occur in children and adolescents, literature describing the effects of such co-occurrence is mixed. There is evidence that symptoms of anxiety disorders may mitigate symptoms of conduct problems (buffering hypothesis) or may exacerbate symptoms of conduct problems (multiple problem hypothesis). A dual-pathway model has been proposed that suggests several possible etiological or risk processes that may differentiate these pathways (i.e., the buffering hypothesis or the multiple problem hypothesis) (Drabick, Ollendick, & Bubier, 2010). Executive functioning is one factor that has been identified that may differentially confer risk to the proposed pathways; however, little research has been done investigating its role. The purpose of the present study was to evaluate the dual-pathway model by determining whether executive functioning abilities contribute to differentiating those youth for whom anxiety exacerbates conduct problems from those for whom anxiety mitigates conduct problems. Specifically, the study sought to examine if executive functioning moderated the effect of anxiety symptom severity on conduct problems. Latent variable structural equation modeling (SEM) was used to analyze the data of 221 youth aged 9 to 16 in a residential treatment center who completed a full neuropsychological evaluation. Results of the study failed to support the hypothesis that executive functioning moderates the effect of anxiety on conduct problems. Furthermore, a structural equation model without an interaction between executive functioning and anxiety was found to fit the data better than a model with an interaction between those variables. Overall, the study found that executive functioning abilities could not distinguish youth for whom anxiety exacerbates conduct problems from youth for whom anxiety mitigates conduct problems. Recommendations for future research in light of the limitations of the current study, as well as remaining gaps in the literature, are discussed. / text

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

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

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