Agriculture is one of the major economic drivers and the production is highly dependable on the climatic conditions and very sensitive to the natural hazards like the flood. The Federal Emergency Management Agency (FEMA) of United States developed Hazard-US model (HAZUS), a tool to estimate the loss to several sectors due to natural hazards like floods, hurricanes, and earthquakes. The study assesses the influence of input model parameters for HAZUS flood loss to crops. This thesis analyzes different combinations of input parameters for the Middle Cedar River Watershed in Iowa. The parameters have been modified based on the cropping pattern of the study region and the pricing trends. The results include the computation of the loss distribution and the determination of the most influential parameters. The study has found that some parameters are more influential in the loss estimation. The influence of parameters for the average annual loss (AAL) calculation is similar. Floods at the end of the cropping season are much more severe than floods at the beginning of the cropping season. Corns are more at risk than soybean because of the longer cropping season. Some counties experience more loss than others based on AAL. The results indicate that the agricultural sector is more vulnerable to floods at the end of the cropping season. The estimation of loss can help emergency planning for floods affecting agriculture, and optimize the agricultural resource management. The inclusion of additional parameters like flood velocity and water quality in the model can increase the accuracy of the estimation.

The three chapters in this dissertation look at different aspects of the labor market and its players. The first chapter estimates the impact of using the internet for job search on job match quality. Using both the semi-parametric Meyer (1990) model and the non-parametric Hausman Woutersen (2014) hazard model, the paper finds that exit rate from employment is at least 28% lower when internet is used as a job search tool. The second chapter looks at the effect of past unemployment on future wages. It is believed that employers may use past unemployment as a signal of low productivity. In this situation workers with a history of unemployment may receive lower wages. The paper uses the Machado Mata (2005) quantile decomposition technique to decompose the wage difference into differences due to characteristics and differences due to rewards. Results indicate that workers with an unemployment spell of more than three months receive at least 12% lower wages and that more than 40% of this wage difference can be attributed to the lower rewards received by the previously unemployed.. The last chapter focuses on human capital formation and looks at some of the reasons behind the low levels of schooling India. Using the Indian Household Development Survey (2005), the paper finds that income continues to be an important factor behind the low level of primary school enrollment. On average, poor students have at least 3% lower enrollment rates, when compared to similar skilled non-poor students.

Investment in higher education is typically considered as a static discrete-choice problem where students make post-secondary education choices usually right after high school (Heckman et al., 2006). This is largely aligned with Becker’s human capital theory. As Becker’s theory holds, students’ decisions can alter with the arrival of new information (Weisbrod, 1964). By relaxing the assumption certainty in the human capital model, student education decisions can be modeled using Weisbrod’s option value theory. According to this theory, students reevaluate their lifetime-utility maximizing decisions based on new information acquired in a sequential nature. Students face large uncertainties due to unexpected positive and negative shocks. This dissertation benefits from utilizing student earnings while in school to proxy for these shocks and opportunity costs. Students test both the schooling and labor market to gain new information to maximize their lifetime earnings. Since higher education choices are dynamic in nature, this dissertation benefits from the use of hazard models as these models explicitly account for time. Overall, the dissertation is largely focused on estimating the effect of time-variant and time-invariant variables on the timing of student higher education investment decision. Time to dropping out or transferring is directly correlated with the cost of education. As students take longer time to transfer or shorter time to drop out, acquiring a bachelor’s degree will take longer. These increases in the cost of education eventually decrease the supply of skilled labor and increase the burden on the state and taxpayers. Using a large administrative data from Kentucky Community and Technical College System (KCTCS) matched with administrative earnings data from Kentucky’s unemployment insurance department, results indicate that increases in student earnings increases time to transfer, decrease time to stopout early and decrease time to graduate. The opportunity cost of continuous enrollment is high and students weigh current events more than future events. Similarly, as students age, the number of years left to enjoy full benefits from another semester of education decreases and hence students are more likely to stopout earlier or transfer later as they age. Lastly, variables that were proxy for ability promote attendance, transfer and graduation.

: Este trabalho tem como objeto o redirecionamento na política externa (RPE) - conceituado como as mudanças mais radicais, abrangentes e rápidas em política externa. Para analisar este fenômeno, são buscadas as principais condições conjunturais que podem aumentar a chance de ocorrência deste evento. Estas condições estão relacionadas ao conceito de Janela Política, que representa o período em que é rompida a inércia política e os tomadores de decisões têm condições de iniciar um processo de RPE. Objetivo: encontrar e delimitar quais as condições conjunturais que aumentam as chances de ocorrência de um RPE. Método: são utilizadas ferramentas metodológicas qualitativas e quantitativas. No segundo capítulo, a análise é feita por meio de um modelo de sobrevivência (Cox Proportional Hazard Model) que analisa o efeito das variáveis sobre os riscos de ocorrência do evento em foco, definido como as alterações mais extremas de comportamento nas votações da Assembleia Geral das Nações Unidas. No terceiro capítulo, é desenvolvida uma análise qualitativa histórica focando especificamente nos casos mais radicais de RPE, buscando identificar padrões comuns no desencadeamento dos processos em estudo; com base nestes casos, são desenvolvidas tipologias explicativas para identificar diferentes caminhos causais que levam ao evento em tela. Resultados: foi identificado que mudanças de regime e de líder político, no âmbito doméstico, e intervenções militares de potências estrangeiras aumentam os riscos de ocorrência de RPE; adicionalmente, a alta polarização política e a mudança de regime, a crise política doméstica com envolvimento de atores internacionais, os processos de isolamento internacional com imposição de sanções econômicas e os períodos de crise econômica com questionamento do modelo econômico vigente por parte dos atores políticos podem combinadamente levar à ocorrência de RPE. Conclusões: apesar da importância do interesses de atores políticos em empreender um projeto de RPE, foi identificado que determinados eventos aumentam os riscos deste processo ocorrer. / This thesis object is the foreign policy restructuring (FPR) - conceptualized as the most radical, encompassing, and fast changes in foreign policy. To analyze this phenomenon, there will be sought the main conjuncture conditions that might enhance the chances of this event occurrence. These conditions are related to the Policy Window concept, that represents a period during which the political inertia is disrupted and decision makers have the circumstances to undertake a FPR process. Objective: find and outline the conjectural conditions and variables that increase the chances of occurrence of a FPR. Methods: it will be used qualitative and quantitative methodological tools. In the second chapter, a survival model (Cox Proportional Hazard Model) analyses the effect variables related to the Policy Window concept over the risks of happening a FPR, defined as the most extreme changes of behavior in United Nations General Assembly roll-call votes. In the third chapter, a historical qualitative analysis is undertaken focusing exclusively on the most radical cases of FPR to develop explanatory typologies in order to identify causal conjunctures and common patters that lead to the outcome. Results: we identified that regime and political leader changes, in the national context, and military interventions by foreign powers enhance the risks of FPR occurrence; additionally, high political polarization combined with regime change, political crisis with international forces involvement, processes of international isolation with economic sanctions enforcement, and economic crises with political actors questioning the current economic model might be combined, configuring causal paths to a FPR. Conclusion: despite the importance of main political actors interest in implementing a FPR process, we identified that specific conjunctures and events raise the risks of a positive outcome.

: Este trabalho tem como objeto o redirecionamento na política externa (RPE) - conceituado como as mudanças mais radicais, abrangentes e rápidas em política externa. Para analisar este fenômeno, são buscadas as principais condições conjunturais que podem aumentar a chance de ocorrência deste evento. Estas condições estão relacionadas ao conceito de Janela Política, que representa o período em que é rompida a inércia política e os tomadores de decisões têm condições de iniciar um processo de RPE. Objetivo: encontrar e delimitar quais as condições conjunturais que aumentam as chances de ocorrência de um RPE. Método: são utilizadas ferramentas metodológicas qualitativas e quantitativas. No segundo capítulo, a análise é feita por meio de um modelo de sobrevivência (Cox Proportional Hazard Model) que analisa o efeito das variáveis sobre os riscos de ocorrência do evento em foco, definido como as alterações mais extremas de comportamento nas votações da Assembleia Geral das Nações Unidas. No terceiro capítulo, é desenvolvida uma análise qualitativa histórica focando especificamente nos casos mais radicais de RPE, buscando identificar padrões comuns no desencadeamento dos processos em estudo; com base nestes casos, são desenvolvidas tipologias explicativas para identificar diferentes caminhos causais que levam ao evento em tela. Resultados: foi identificado que mudanças de regime e de líder político, no âmbito doméstico, e intervenções militares de potências estrangeiras aumentam os riscos de ocorrência de RPE; adicionalmente, a alta polarização política e a mudança de regime, a crise política doméstica com envolvimento de atores internacionais, os processos de isolamento internacional com imposição de sanções econômicas e os períodos de crise econômica com questionamento do modelo econômico vigente por parte dos atores políticos podem combinadamente levar à ocorrência de RPE. Conclusões: apesar da importância do interesses de atores políticos em empreender um projeto de RPE, foi identificado que determinados eventos aumentam os riscos deste processo ocorrer. / This thesis object is the foreign policy restructuring (FPR) - conceptualized as the most radical, encompassing, and fast changes in foreign policy. To analyze this phenomenon, there will be sought the main conjuncture conditions that might enhance the chances of this event occurrence. These conditions are related to the Policy Window concept, that represents a period during which the political inertia is disrupted and decision makers have the circumstances to undertake a FPR process. Objective: find and outline the conjectural conditions and variables that increase the chances of occurrence of a FPR. Methods: it will be used qualitative and quantitative methodological tools. In the second chapter, a survival model (Cox Proportional Hazard Model) analyses the effect variables related to the Policy Window concept over the risks of happening a FPR, defined as the most extreme changes of behavior in United Nations General Assembly roll-call votes. In the third chapter, a historical qualitative analysis is undertaken focusing exclusively on the most radical cases of FPR to develop explanatory typologies in order to identify causal conjunctures and common patters that lead to the outcome. Results: we identified that regime and political leader changes, in the national context, and military interventions by foreign powers enhance the risks of FPR occurrence; additionally, high political polarization combined with regime change, political crisis with international forces involvement, processes of international isolation with economic sanctions enforcement, and economic crises with political actors questioning the current economic model might be combined, configuring causal paths to a FPR. Conclusion: despite the importance of main political actors interest in implementing a FPR process, we identified that specific conjunctures and events raise the risks of a positive outcome.

Cox proportional hazard model is often used to estimate the effect of covariates on hazard for censored event times. In this thesis we study the semiparametric models of additive risk for censored data. In this model the hazard is given as a sum of unknown baseline hazard function and a product of covariates and coefficients. Further the general additive-multiplicative model is assumed. In this model the effect of a covariate can be either multiplicative, additive or both at the same time. We focuse on determining the effect of a covariate in the general model. This model can be used to test for the multiplicative or addtive effect of a covariate on the hazard.

以往重複事件分析法主要用於醫學與科學領域，近來學者逐漸將其應用至經濟、商學、社會科學等領域，本篇論文採用重複事件分析法，分析S&P 500公司股票回購的行為，回顧過去學者對股票回購之研究，我們檢視公司執行股票回購的三大原因，根據我們的實證結果發現公司可能會以股票回購作為影響公司資本結構的工具，再者亦可能用以減低剩餘資金，然而，本篇論文的實證結果較不支持訊號發射理論。 / In this study, we apply Cox proportional hazard model in recurrent event analysis, which usually used in medical and science studies, to analyze the determinants of the stock repurchase events of S&P 500 companies. We investigate three main incentives that companies conduct stock repurchase. The empirical results show that companies employ repurchase as a technique to alter capital structure. In addition, companies conduct stock repurchase to distribute excess capital. In contrast, there are little evidences to support signaling undervaluation.

The United States has a long history of domestic terrorism, yet U.S. counterterrorism policy has focused almost completely on the threat from international terrorism. The gap in the literature was the absence of an empirical evaluation of U.S. counterterrorism policy on domestic terrorism in general. The purpose of this quantitative study was to describe the impact of 21st century U.S. counterterrorism policy on incidence, lethality, and cost of domestic terrorism using data from the Global Terrorism Database. The multiple streams framework and the power elite theory were used. In this longitudinal trend study using secondary data analysis, domestic terrorism data were analyzed from 749 terrorist attacks using descriptive statistics, visual analysis, and the series hazard model to examine any changes in the frequency and hazard of domestic terrorism in relation to the following 5 policies: USA PATRIOT Act, USA PATRIOT Improvement and Reauthorization Act, Animal Enterprise Terrorism Act, Implementing Recommendations of the 9/11 Commission Act, and USA FREEDOM Act. The results empirically supported the greater threat of domestic terrorism and showed that domestic terrorism changed in relation to counterterrorism policy. Further, the addition of the series hazard model in the analysis of domestic terrorism following policy implementation added additional depth to the results. This study contributed to positive social change by providing policy makers and counterterrorism agencies with an empirical, evidence-based method for evaluating U.S. counterterrorism policy and for a non-partisan, non-political, evidence-based method for quantitatively determining terrorist threat.

In this paper, we estimate the parameters $S_0(t)$ and $ eta$ in Cox proportional hazard model when data are all interval-censored. For the application of this model, data should be either exact or right-censored, therefore we transform interval-censored data into exact data by three di®erent methods and then apply Nelson-Aalen estimate to obtain $S_0(t)$ and $ eta$. The test statistic $hat{ eta}^2I(hat{ eta})$ is not approximately distributed as $chi^2_{(1)}$ but $chi^2_{(1)}$ times a constant c.

In this thesis, we examine labor market outcomes for the youth (ages 15-29) using microdata from several rounds of the Turkish Household Labor Force Survey (HLFS). We begin by examining demographic trends. We then rely on synthetic cohorts. The fact that the HLFS sample frame targets the civilian non-institutional population brings about difficulties in interpreting labor market indicators. We show that a more reasonable picture of schooling and work choices emerges when a simple correction for &lsquo / missing males&rsquo / who are doing their CMS and examine the effect of Compulsory Military Service (CMS) on the transition from school to work by using discrete hazard models. We also investigate the time it takes to find the first permanent job to shed light on the recent evolution of the transition from school to work.Using Cox Proportional Hazard Model, we examine the effects of structural reforms and macro-economic conditions, and the permanence of these effects. We are able to study the differences in the hazard of obtaining the first permanent job by education levels non-parametrically. Finally, we investigate the changes in the cumulative baseline hazards over time and test for the presence of gender differences in the hazard rates by using time varying covariates. With the help of these covariates, we are able to compute the time needed for the closure of the gender gap.