Graduate students represent 15% of the students and one-third of the graduates of colleges and universities across the United States. They are leading thinkers in higher education institutions and businesses across the country and around the world. In many fields, such as law, graduate or professional school is required for entry-level employment, whereas in other fields, such as business, graduate education may enhance performance and opportunities for promotion. The educational stratification and college-choice literature document the influence of family background (distal family) on educational attainment. These literatures focus on the traditional undergraduate student without considering the different preferences and responsibilities (context) of potential graduate students considering enrollment. Potential graduate students are often older than high school students making a college choice, are independent from their parents, and may have a spouse and children (proximal family) at the forefront of their educational plans. This dissertation builds on the educational stratification and college-choice literature by considering post-baccalaureate (graduate) enrollment specifically. This study explores the effects of marriage, parenthood, and any corresponding gender effects on whether and when a bachelor's degree recipient enrolls in graduate education. To investigate these proximal family effects and gender effects, I analyzed data from the National Center for Education Statistics' Baccalaureate and Beyond Longitudinal Study 1993/03--a longitudinal study that surveyed over 11,000 students at the time of their bachelor's degree completion and three additional times over 10 years. Using survival analysis (event history analysis), I measured the amount of time between baccalaureate degree completion and first graduate enrollment. Using this measure, I compared differences in the odds of graduate enrollment and timing of graduate enrollment based on marital status, parental status, and gender. Overall, more women than men enrolled in graduate education, and men enrolled sooner than women. The results showed that being a parent had a negative effect on if and when an individual enrolled in graduate school. Being married also had a negative effect on if and when an individual enrolled in graduate school, with married men experiencing a slightly stronger negative effect than married women. The combined effect of being married and being a parent had the strongest negative effect on graduate enrollment for men and women, but more so for women. By better understanding graduate college choice, institutions can more effectively use resources and improve the opportunities and experiences for graduate students and, specifically, graduate students with families. Minimizing barriers to entry may level the playing field between graduate degree aspirants with families and those without families.

Over the years, the time that students take to attain the doctorate, particularly in Education, has been increasing. Given the cost incurred in preparing students, the decrease in years of productivity in the chosen professions, and other opportunity costs, this trend is of great concern to students, the university, and society at large. This dissertation examined the timing of doctorate attainment and the factors related to this timing. Using secondary data (N=1,028 students), discrete-time multilevel hazard analysis was employed to determine the relationship between various factors and the timing of doctorate attainment in a College of Education. Complementary to the quantitative analyses, four student and two faculty focus groups and four follow-up student interviews were conducted to identify factors perceived to influence time to attainment of the doctorate (TTD) in one College of Education at a state university. Discrete-time multilevel hazard analysis revealed that the median TTD in Education was 5.8 years; students were most likely to attain the doctorate in the seventh year. In each year during the observation period, students' master's grade point average (GPA) score at admission, percentage of female students in the program, and mean graduate record examination (GRE) quantitative score in the program were each positively associated with the odds of doctorate attainment; whereas the size of the department housing the program was negatively associated with the odds of doctorate attainment. Female students were more likely than males to attain the doctorate in each year during the observation period, however, the difference disappeared when clustering of students into programs was considered. According to students, the way program expectations and requirements are communicated, the nature of the dissertation committee formed, and dissertation topic chosen each had a strong association with TTD. Faculty perceived that whether a student enrolls part-time or full-time, the amount and quality of academic preparation received, and the nature of academic guidance, mentoring and supervision received, each had a strong association with TTD. Both students and faculty concurred that the nature and arrangement of program tasks and resources and the desire to work and attain goals despite obstacles encountered had strong associations with TTD. Implications for policy and practice and suggestions for future research are discussed.

While extensive research has been conducted on the causes of intimate partner violence in the community, very little is known about rates and predictors of domestic violence perpetrated by offenders who have recently been incarcerated. Some evidence suggests that formerly incarcerated individuals may be at an increased risk to perpetrate intimate partner violence during the transition from prison to the community (e.g., Hairston & Oliver 2006; Hilton, Harris, Popham, & Lang, 2010; Oliver & Hairston, 2008). The primary goal of this dissertation was to examine the extent to which former inmates engage in domestic violence during the transition from prison to the community. A second goal of this dissertation was to determine the independent and interactive effects of selected individual, situational, and social-structural factors on post-prison domestic violence. The current dissertation project involved a retrospective study of data collected from n = 1,137 formerly-incarcerated male offenders who were released from state prison between 2004 and 2009. Data regarding individual-level factors of borderline and antisocial personality characteristics and exposure to family-of-origin violence were extracted from institutional records. Additional individual-level demographic characteristics including offenders' age, ethnicity, education need, marital status, number of children, crime of conviction, length of incarceration, and participation in correctional rehabilitation programs extracted from institutional records were also considered. The situational-level factor of offenders' employment after prison release was also collected from institutional records; and the social-structural factor of neighborhood disadvantage was collected from information available in offenders' community supervision records and Census tract-level data. The outcome measure of post-prison domestic violence was gathered from local law enforcement records. Data were entered into statistical models to predict post-prison domestic violence. Main effects on post-prison domestic violence were examined for each of the individual-level demographic characteristics, borderline and antisocial personality features, exposure to family-of-origin violence, employment, and neighborhood disadvantage. Interactive effects on post-prison domestic violence were examined between borderline and antisocial personality characteristics, exposure to family-of-origin violence, employment, and neighborhood disadvantage. Significant predicted main effects on post-prison domestic violence included age, ethnicity, education need, number of children, violent criminal history, attendance of substance abuse treatment in prison, witnessing interparental violence as a child, and neighborhood disadvantage. Significant predicted interaction effects on post-prison domestic violence included the interaction between physical abuse as a child and neighborhood disadvantage. Implications for policies regarding post-prison supervision sentencing, housing, and the advancement of programming to prevent intimate partner violence during the transition from prison to the community are discussed. Contributions to the literature on intimate partner violence, environmental transition theory, and ecological theoretical frameworks are also addressed.

Objectives: This retrospective cohort study aimed to assess the survival time and factors associated with survival of anterior composite-resin restoration placed at the University of Iowa, College of Dentistry (UICOD). Methods: Patients at the UICOD who had anterior composite restorations placed between 1995-1997 and could be followed through 2013 were included in this study. Factors included: patient age and gender, tooth type (central or lateral incisor, or canine) and location (maxillary or mandibular), restoration size (1, 2, 3, 4 and more surfaces), provider type (dental student, graduate student, faculty), and clinic (operative, family, or other clinics) where the initial restoration placed. Survival time of a restoration was defined as how long a restoration lasted from the day of placement until the day of subsequent treatment. Subsequent treatment included: restorations, veneer and/or crowns, root canal therapy, and extraction. One restoration per patient was used for the study. Statistical analyses consisted of the Kaplan-Meier analysis and Cox regression (alpha=0.05). Results: Of the 668 subjects (mean±SD age=55±13 years and 60.8% females) who fulfilled the inclusion criteria, the mean±SD survival time of composite resin restoration was 11±7 years and an overall survival rate was 43.3%. Patients' gender, age, tooth location, and clinic type were not significantly associated with the survival time of composite resin restoration. Cox regression model indicated that significant differences in the restoration hazards were found on tooth type (p=0.002), provider type (p=0.003) and restoration sizes (p=0.0072). Central (HR=1.59; CI=1.23-2.07) and lateral (HR=1.36; CI=1.03-1.79) incisors had a significantly higher hazard ratio (HR) than canines, and faculty had significantly lower HR than undergraduate students (HR=0.68, CI=0.55-0.85). Restorations sizes one surface (HR=0.6; CI=0.44-0.81) and two surfaces (HR=0.65; CI=0.48-0.88) had significantly lower HR than four and more surfaces restorations. Conclusion: The mean and median survival time of anterior composite restoration at UICOD was 11 and 13 years, respectively. Tooth type, provider type, and restoration size were significant predictors for the survival time of anterior composite-resin restoration.

The objective of the present study is to investigate key aspects of ovarian and breast cancers, which are two main causes of mortality among women. Identification of the true behavior of survivorship and influential risk factors is essential in designing treatment protocols, increasing disease awareness and preventing possible causes of disease. There is a commonly held belief that African Americans have a higher risk of cancer mortality. We studied racial disparities of women diagnosed with ovarian cancer on overall and disease-free survival and found out that there is no significant difference in the survival experience among the three races: Whites, African Americans and Other races. Tumor sizes at diagnosis among the races were significantly different, as African American women tend to have larger ovarian tumor sizes at the diagnosis. Prognostic models play a major role in health data research. They can be used to estimate adjusted survival probabilities and absolute and relative risks, and to determine significantly contributing risk factors. A prognostic model will be a valuable tool only if it is developed carefully, evaluating the underlying model assumptions and inadequacies and determining if the most relevant model to address the study objectives is selected. In the present study we developed such statistical models for survival data of ovarian and breast cancers. We found that the histology of ovarian cancer had risk ratios that vary over time. We built two types of parametric models to estimate absolute risks and survival probabilities and to adjust the time dependency of the relative risk of Histology. One parametric model is based on classical probability distributions and the other is a more flexible parametric model that estimates the baseline cumulative hazard function using spline functions. In contrast to women diagnosed with ovarian cancer, women with breast cancer showed significantly different survivorship among races where Whites had a poorer overall survival rate compared to African Americans and Other races. In the breast cancer study, we identified that age and progesterone receptor status have time dependent hazard ratios and age and tumor size display non-linear effects on the hazard. We adjusted those non-proportional hazards and non-linear effects by using an extended Cox regression model in order to generate more meaningful interpretations of the data.

The objective of this study is to address some important questions associated with stomach cancer patients using the data from the Surveillance Epidemiology and End Results (SEER) program of the United States. To better understand the behavior of stomach cancer, we first perform parametric analysis for each patient group (white male, white female, African American male, African American female, other male and female) to identify the probability distribution function which can best characterize the behavior of the malignant stomach tumor sizes. We evaluate the effects of patients’ age, gender and race on the malignant stomach tumor sizes by developing quantile regression models, which gives us a better understanding of the behavior of the malignant stomach tumors. We also proposed statistical models with respect to patients’ malignant stomach tumor size as a function of age for different races and gender group, respectively. The proposed models were evaluated to attest their prediction quality. Furthermore, we have identified the rate of change of the malignant tumor size as a function of age, for gender and race. We evaluated the routine treatment of stomach cancer using parametric and nonparametric survival analysis. We have found that stomach cancer patients who receive surgery with radiation together have a better survival probability than the patients who receive only radiation. We performed decision tree analysis to assist the physician in recommending to his patients the most effective treatment that is a function of their characteristics.

The performance of different pavement maintenance treatments were evaluated by investigating practical projects collected from Tennessee Pavement Management System (PMS) and Long Term Pavement Performance (LTPP) database. The influence of factors on the effectiveness, cost-effectiveness and cracking initiation of different treatment were evaluated by “Optime”, multiple linear regression and parametric survival analysis. Pavement roughness, pavement serviceability index (PSI) and the initiation time of cracking were used as pavement performance indicators. Investigation on the pavement maintenance projects in Tennessee by Optime and multiple linear regression analysis indicated that HMA overlay had the highest effectiveness, followed by mill & fill and micro surfacing. Due to the relatively low cost, micro surfacing was the most cost-effective treatment, followed by HMA overlay and mill & fill. The effectiveness and cost-effectiveness decreased with the increase of traffic level and pre-treatment pavement condition. Investigation on the LTPP resurfacing treatments indicated that thick overlay and milling reduced the roughness after rehabilitation. Thin overlay, high traffic level and poor pre-rehabilitation pavement condition increased the deterioration rate of new overlay. Using reclaimed asphalt material did not influence the treatment performance but was cost-effective in reducing the roughness of new overlay. For a certain deterioration rate, there was an optimized pre-rehabilitation roughness value or time for applying maintenance treatment. Survival analysis on the crack initiation of asphalt overlay indicated that high traffic level accelerated the initiation of cracking. Thick overlay delayed the initiation of cracking except for the non-wheel path longitudinal crack. Mill retarded the occurrence of the non-fatigue cracks, whereas severe freeze thaw condition accelerated the occurrence of the two types of cracking. Using 30% RAP accelerated the initiation of longitudinal fatigue crack on wheel path but did not cause serious fatigue problem. The performance curves of HMA resurfacing treatments used in Tennessee were calibrated by investigating the influence of different factors on the slopes and intercepts of post-treatment performance curves. The analysis indicated that pavement with high pre-treatment PSI, thick overlay and deep milling had low deterioration rate, whereas pavement with higher traffic level deteriorated faster.

A unique approach is developed for evaluating Human Capital (workforce) requirements. With this approach, new ways of measuring personnel availability are proposed and available to ensure that an organization remains ready to provide timely, relevant, and accurate products and services in support of its strategic objectives over its planning horizon. The development of this analysis and methodology was established as an alternative approach to existing studies for determining appropriate hiring and attrition rates and to maintain appropriate personnel levels of effectiveness to support existing and future missions. The contribution of this research is a prescribed method for the strategic analyst to incorporate a personnel and cost simulation model within the framework of Human Resources Human Capital forecasting which can be used to project personnel requirements and evaluate workforce sustainment, at least cost, through time. This will allow various personnel managers to evaluate multiple resource strategies, present and future, maintaining near “perfect” hiring and attrition policies to support its future Human Capital assets.

The subject of this thesis concerns pricing the use of transport infrastructure. We are empirically investigating the relationship between railway traffic volumes and infrastructure management costs. More specifically, we are interested in estimating the change in infrastructure management costs from marginal variations in traffic volumes, i.e. to estimate the marginal cost of railway infrastructure wear and tear. Both Europe and Sweden have moved towards a marginal cost based transport pricing policy, thus driving the need for more empirical work on rail infrastructure costs to underpin the level of a wear and tear charge. The thesis consists of five papers. In paper I, the data situation for planning railway maintenance and renewal is surveyed internationally. The survey indicates that most infrastructure managers are still in the data gathering phase, rather than ready to use modern computerised planning tools to make sound decisions in the field of maintenance and renewal. In paper II, we investigate the data situation for infrastructure cost analysis in Sweden. A panel data set that consists of cost, traffic and infrastructure information is created. The data covers 1999-2002 and contains almost 190 annual observations. Three main cost categories are identified; infrastructure operation, maintenance and renewal. This data is used for estimations of cost functions in paper II, III and V. Econometric techniques are applied for this purpose, with several different model specifications. In paper II, the method of pooled ordinary least squares (POLS) is applied. In paper III, we turn to unobserved effects models to exploit data heterogeneity. Finally in paper V, a dynamic generalised method of moments estimator is used to explore a potential dynamic cost dependency. The main findings are that the POLS approach, which has been used in similar studies in Europe recently, is rejected in favour of fixed effects estimation for this data. Furthermore, we also reject the idea of regression analysis to capture marginal rail renewal costs. In paper IV, we suggest an analytical expression combined with survival analysis of rail ages to estimate marginal renewal costs. We derive elasticities with respect to output as well as marginal costs for the different cost categories, and find that the current charge for wear and tear in Sweden is well below these new estimates. This opens up for increased, marginal cost based rail infrastructure wear and tear charges, which would reduce the financial burden on Swedish tax-payers. / QC 20100622

<p>The aim of this study is to illustrate, adapt and develop methods of survival analysis in analysing and estimating customer survival time in subscription-based businesses. Two particular objectives are studied. The rst objective is to redene the existing survival analysis techniques in business terms and to discuss their uses in order to understand various issues related to the customer-rm relationship.</p>