In the dissertation, a monotone spline-based nonparametric estimation method is proposed for analyzing longitudinal data with mixture distributions. The innovative and efficient algorithm combining the concept of projected Newton-Raphson algorithm with linear mixed model estimation method is developed to obtain the nonparametric estimation of monotone B-spline functions. This algorithm provides an efficient and flexible approach for modeling longitudinal data monotonically. An iterative 'one-step-forward' algorithm based on the K-means clustering is then proposed to classify mixture distributions of longitudinal data. This algorithm is computationally efficient, especially for data with a large number of underlying distributions. To quantify the disparity of underlying distributions of longitudinal data, we also propose an index measure on the basis of the aggregated areas under the curve (AAUC), which makes no distributional assumptions and fits the theme of nonparametric analysis. An extensive simulation study is conducted to assess the empirical performance of our method under different AAUC values, covariance structures, and sample sizes. Finally, we apply the new approach in the PREDICT-HD study, a multi-site observational study of Huntington Disease (HD), to explore and assess clinical markers in motor and cognitive domains for the purpose of distinguishing participants at risk of HD from healthy subjects.

Objective: This retrospective longitudinal study attempts to determine the ontogenetic patterning of nasal septal deviation and if there is a relationship between a deviated septum and facial form growth and development. Methods: Nineteen females and twenty males were selected from the Iowa Facial Growth Study. Eighteen lateral cepalometric variables were analyzed and septal deviation was quantified using a percentage of deviation. A generalized Procrustes analysis was used to scale landmarks and generate principal components. Pearson correlation coefficients were used to analyze differences in shape. A Mann Whitney U-Test was used to analyze changes in septal deviation. Results: The first three principal components explained 56.23% of the variance. Only PC1 was significantly correlated with centroid size (r=0.82, P<0.0001). Mean percentage of septal deviation (0.620% ± 0.463%) was present at the youngest age group (3-4.9 years) and increased in each age group until adulthood, defined as over the age of 20 (0.991% ± 0.519). None of the first three principal components were found to be correlated to percentage of septal deviation. Conclusions: Nasal septal deviation has been found to increase in a longitudinal sample of subjects of northern European descent. Nasal septal deviation represents a disjunction in the growth of the nasal septum with the rest of the face. The amount and timing of nasal septal deviation that can cause nasal obstructions leading to vertical growth changes was not analyzed in this study and will require future study.

This study examined the school functioning of children with asthma compared to the school functioning of children without asthma over a 9-year time span. The present study was a secondary analysis of data from one large school district in a southeastern state. Information was gathered from multiple sources, including student records and parent and teacher surveys. Variables related to academics, behavior, and teacher perception were examined. A total of 646 participants were initially included in the study. These participants included 296 students identified as having asthma and 350 students identified as not having asthma. Participants were matched on gender, race, and socioeconomic status. Results of this study indicated significant differences for various years and subjects on a standardized achievement test. However, computed effect sizes were quite low, suggesting no practical difference between the groups. Additionally, rates of special education placement differed for the groups for one school year. All other years and variables indicated no significant differences between the groups. These findings suggest that educational experience of children with asthma may not differ significantly from that of their peers without asthma. However, future research should attempt to measure variables in different ways and possibly examine cases in a more qualitative manner.

Utilization of a large, diverse sample provided a rare opportunity to advance our understanding of gender, race, and socioeconomic differences in school-based problem behavior. Yearly assessment of discipline referrals and suspensions received within the school context from 5th- through 11th-grade, as well as assessment of school dropout, provided an opportunity to examine these issues through an extended prospective longitudinal design. Results highlight the middle school transition as a time when discipline referrals and suspensions increase markedly, while student reports of connections to others, motivation, and optimism decline sharply. Results indicate that boys, African-American students, and students from low socioeconomic status backgrounds report lower levels of connections to others, motivation, and optimism in 5th-grade. Boys, African-American students, and students from low socioeconomic status backgrounds also receive more discipline referrals and suspensions from 5th-grade onward and are more likely to experience dropout. However, regardless of demographic group membership, students who report stronger connections to others, motivation, and optimism in 5th-grade receive fewer referrals and suspensions from 5th- through 11th grade, and are much less likely to dropout of school than are students who report lower levels of connections, motivation, and optimism in 5th-grade. These results highlight the need to address students' sharp declines in functioning across the middle school transition through both ecological and person-centered prevention and school restructuring efforts. Results also highlight the utility of movement away from a static, demographic based understanding of problem behavior toward a clearer understanding of person and environment factors that may underlie both between and within demographic group differences in outcomes. Placing emphasis upon factors that are potentially amenable through school based prevention efforts considerably increases the likelihood that all of our nation's children are provided with equal opportunity to achieve their fullest potential.

The purpose of this study was to examine the perceptions of participants involved in one community college's strategic planning process in which faculty, administrators, and staff at all levels of the organization were encouraged to participate. Data were collected through direct observation, focus group interviews, analysis of institutional documents, and a pen and paper questionnaire. Data were analyzed through a constant comparative method. Reduction of the data produced themes exploring the reaction of participants to the new strategic planning process. This qualitative study generated four hypotheses that relate to these research questions: 1. Staff participation in an organization's strategic planning process results in a deeper staff understanding of the organization's mission, a higher staff commitment to the organization's goals, and a demonstration of greater staff energy and vitality. 2. Community college departments will interpret and implement institutional strategic planning processes in ways that are unique and congruent with their academic discipline; a single process cannot be successfully dictated. 3. When managers serve as facilitators or use others to facilitate strategic planning processes, staff will self-organize, a process will emerge, and leadership will take a variety of forms. 4. Community college staff who encounter change in strategic planning processes can be categorized as Guarded Optimists, Curmudgeons, Crusaders, or Along for the Ride, based on levels of frustration and optimism. Recommendations for Practice: 1. Obtain acceptance of terminology from all units before beginning the participatory strategic planning process. Use acceptable terms in form/templates and in facilitation. 2. Do not dictate a single process for strategic planning across all disciplines. Design forms and processes that are adaptable to differences in styles of critical thinking. 3. Use facilitators to assist units in the participatory strategic planning effort. Train the facilitators to work in ways that empower participants. 4. Reduce participant frustration and increase optimism by providing sufficient time, creating sustainable feedback loops, both of which demonstrate that the unit manager has thought through the process. 5. Increase participation in strategic planning processes to gain deeper understanding of the organization's mission, higher commitments to organizational goals, and a demonstration of greater energy and vitality. / Graduation date: 1998

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on Feb. 5, 2007). Thesis advisor: Ralph D. Kimberlin. Vita. Includes bibliographical references.

Today, health problems are likely to have a complex and multifactorial etiology, whereby psychosocial factors interact with behaviour and bodily responses. Women generally report more health problems than men. The present thesis concerns the development of women’s health from a subjective and objective perspective, as related to psychosocial living conditions and physiological stress responses. Both cross-sectional and longitudinal studies were carried out on a representative sample of women. Data analysis was based on a holistic person-oriented approach as well as a variable approach. In Study I, the women’s self-reported symptoms and diseases as well as self-rated general health status were compared to physician-rated health problems and ratings of the general health of the women, based on medical examinations. The findings showed that physicians rated twice as many women as having poor health compared to the ratings of the women themselves. Moreover, the symptom ”a sense of powerlessness” had the highest predictive power for self-rated general health. Study II investigated individual and structural stability in symptom profiles between adolescence and middle-age as related to pubertal timing. There was individual stability in symptom reporting for nearly thirty years, although the effect of pubertal timing on symptom reporting did not extend into middle-age. Study III explored the longitudinal and current influence of socioeconomic and psychosocial factors on women’s self-reported health. Contemporary factors such as job strain, low income, financial worries, and double exposure in terms of high job strain and heavy domestic responsibilities increased the risk for poor self-reported health in middle-aged women. In Study IV, the association between self-reported symptoms and physiological stress responses was investigated. Results revealed that higher levels of medically unexplained symptoms were related to higher levels of cortisol, cholesterol, and heart rate. The empirical findings are discussed in relation to existing models of stress and health, such as the demand-control model, the allostatic load model, the biopsychosocial model, and the multiple role hypothesis. It was concluded that women’s health problems could be reduced if their overall life circumstances were improved. The practical implications of this might include a redesign of the labour market giving women more influence and control over their lives, both at and away from work.

Ankylosing spondylitis (AS) is a chronic, inflammatory rheumatic disease that has a highly variable disease course. Three biologic agents, adalimumab, etanercept, and infliximab, have been developed for the treatment of AS. We conducted three studies: 1) an exploratory analysis of a year-long longitudinal dataset to gain insight into the variability of disease activity, physical function, and well-being and to explore the relationship between these outcome measures; 2) a systematic review of the available evidence for the efficacy of biologic treatment; 3) a systematic review of potential adverse effects of this treatment. We found that repeated measures of disease activity, function and well-being fluctuate considerably between patients, with complex patterns occurring over time within patients. There was mostly high quality evidence that these biologics are efficacious against placebo. We did not find evidence of an increase in serious adverse events or serious infections from short-term randomized controlled trials.

This research was conducted in the Mamora cork oak forest of Morocco to: (1) Describe the impacts of sheep grazing (none, 35% use, 70% use) in March, April, May and June of 1987 and 1988 on seasonal forage production; (2) evaluate the effects of these factors on annual changes in herbaceous foliar cover and botanical composition; and (3) determine their effects on seasonal changes in forage quality of the herbaceous vegetation. Neither the month of 1987 nor the degree of use had significant effects on the rate of herbage accumulation. In 1988, the month of grazing, the degree of use and their interaction had significant effects on all rates of herbage accumulation except that between May and June for the March grazed treatment. For the April, May and June treatments, grazing depressed the forage production of the subsequent months. The interaction of the month of grazing and the degree of use had no significant effect on the botanical composition of all groups of species. Averaged over the season, the other forbs were the dominant group of species. Total canopy cover was significantly affected by the year only. The 1988 total vegetative ground cover was significantly higher than the 1987 and 1989 ones as a result of the impacts of the intensity and distribution of rains on vegetative growth, development and distribution. The degree of use had a significant effect on the forage nutrients only for some grazing treatments. It seemed that the effect of the grazing intensity on forage nutrients of the subsequent months is more evident when grazing occurs early in the season. This study developed the first information for this area related to the response of the vegetation to the time and the intensity of grazing. The results suggest that scheduling intensity and timing of grazing livestock might be a key factor in community dynamics. Combined research on grazing management, fertilization and seeding should be undertaken and implemented in the next Mamora management plan. / Graduation date: 1992

Data obtained from longitudinal surveys using complex multi-stage sampling designs contain cross-sectional dependencies among units caused by inherent hierarchies in the data, and within subject correlation arising due to repeated measurements. The statistical methods used for analyzing such data should account for stratification, clustering and unequal probability of selection as well as within-subject correlations due to repeated measurements. <p>The complex multi-stage design approach has been used in the longitudinal National Population Health Survey (NPHS). This on-going survey collects information on health determinants and outcomes in a sample of the general Canadian population. <p>This dissertation compares the model-based and design-based approaches used to determine the risk factors of asthma prevalence in the Canadian female population of the NPHS (marginal model). Weighted, unweighted and robust statistical methods were used to examine the risk factors of the incidence of asthma (event history analysis) and of recurrent asthma episodes (recurrent survival analysis). Missing data analysis was used to study the bias associated with incomplete data. To determine the risk factors of asthma prevalence, the Generalized Estimating Equations (GEE) approach was used for marginal modeling (model-based approach) followed by Taylor Linearization and bootstrap estimation of standard errors (design-based approach). The incidence of asthma (event history analysis) was estimated using weighted, unweighted and robust methods. Recurrent event history analysis was conducted using Anderson and Gill, Wei, Lin and Weissfeld (WLW) and Prentice, Williams and Peterson (PWP) approaches. To assess the presence of bias associated with missing data, the weighted GEE and pattern-mixture models were used.<p>The prevalence of asthma in the Canadian female population was 6.9% (6.1-7.7) at the end of Cycle 5. When comparing model-based and design- based approaches for asthma prevalence, design-based method provided unbiased estimates of standard errors. The overall incidence of asthma in this population, excluding those with asthma at baseline, was 10.5/1000/year (9.2-12.1). For the event history analysis, the robust method provided the most stable estimates and standard errors. <p>For recurrent event history, the WLW method provided stable standard error estimates. Finally, for the missing data approach, the pattern-mixture model produced the most stable standard errors <p>To conclude, design-based approaches should be preferred over model-based approaches for analyzing complex survey data, as the former provides the most unbiased parameter estimates and standard errors.