The aim of this thesis is to empirically analyze the behavior of terrorist groups. In this work we tested the assumption of the model of rational choice in terms of terrorism. The empirical section combines theoretical predictions with observed facts and shows the terrorists as rational actors acting under uncertainty. The data used in the analysis orginate from databases GTD and RDWTI. Mean-variance analysis of portfolios of real attack of terrorist organizations suggests their ability to effectively optimize their activity and to reduce the risks to which they are exposed. Terrorists thus appears as rational agents able to react quickly to external influences. This largely affects the resulting impact of counter-terrorism measures taken when selectively targeted measures may lead to a mere transfer of terrorist activity to another destination.

The existing estimation techniques for grouped data models can be analyzed as a class of estimators of instrumental variable-Generalized Method of Moments (GMM) type with the matrix of group indicators being the set of instruments. Econometric literature (e.g. Smith, 1997; Newey and Smith, 2004) show that, in some cases of empirical relevance, GMM can have shortcomings in terms of the large sample behaviour of the estimator being different from the finite sample properties. Generalized Empirical Likelihood (GEL) estimators are developed that are not sensitive to the nature and number of instruments and possess improved finite sample properties compared to GMM estimators. In this thesis, with the assumption that the data vector is iid within a group, but inid across groups, we developed GEL estimators for grouped data model having population moment conditions of zero mean of errors in each group. First order asymptotic analysis of the estimators show that they are √N consistent (N being the sample size) and normally distributed. The thesis explores second order bias properties that demonstrate sources of bias and differences between choices of GEL estimators. Specifically, the second order bias depends on the third moments of the group errors and correlation among the group errors and explanatory variables. With symmetric errors and no endogeneity all three estimators Empirical Likelihood (EL), Exponential Tilting (ET) and Continuous Updating Estimator (CUE) yield unbiased estimators. A detailed simulation exercise is performed to test comparative performance of the EL, ET and their bias corrected estimators to the standard 2SLS/GMM estimators. Simulation results reveal that while, with a few strong instruments, we can simply use 2SLS/GMM estimators, in case of many and/or weak instruments, increased degree of endogeneity, or varied signal to noise ratio, bias corrected EL, ET estimators dominate in terms of both least bias and accurate coverage proportions of asymptotic confidence intervals even for a considerably large sample. The thesis includes a case where there are within group dependent data, to assess the consequences of a key assumption being violated, namely the within-group iid assumption. Theoretical analysis and simulation results show that ignoring this feature can result in misleading inference. The proposed estimators are used to estimate the returns to an additional year of schooling in the UK using Labour Force Survey data over 1997-2009. Pooling the 13 years data yields roughly the same estimate of 11.27% return for British-born men aged 25-50 using any of the estimation techniques. In contrast using 2009 LFS data only, for a relatively small sample and many weak instruments, the return to first degree holder men is 13.88% using EL bias corrected estimator, where 2SLS estimator yields an estimate of 6.8%.

The main aim of this dissertation is to investigate whether the price convergence between new and old EU member countries occurred. According to development of price level index it is shown that new member countries converge towards the EU27 and that old member countries more or less hover around their initial levels. Germany is chosen to be a benchmark country and thus the development towards Germany is also examined. The results reveal that new member states converge towards the benchmark country. However, in the case of old member states both convergence and divergence occurs. Furthermore, factors that may have an influence on such a development are investigated. The empirical research shows that GDP, hiring regulations and minimum wage and business regulation were of significance during the examined period, from 2000 to 2009 respectively.

Measuring Biodiversity is an important phenomenon to serve best to our ecology and also keep environment sound. Variety of life on different levels, like an ecosystem, life forms on a site, landscape collectively known as Biodiversity. Species richness and evenness combine measures as Biodiversity. Separate formula, index, equation are widely using to measure Biodiversity in each level. Swedish Environmental Protection Agency aimed to establish an index that consists of landscape functionality and landscape heterogeneity. For landscape functionality assessment, there BBCI (Biotope biodiversity Capacity index) is going to use. High BBCI indicates a high biodiversity for each biotope. However, empirically estimate species richness how much matched with BBCI that not been evaluated. The aim of this paper to see the relationship between empirical estimated Biodiversity and BBCI. A relationship between Shannon diversity index and BBCI also ran to see the matches between them. Collect the empirical data from selected 15 landscapes using Artportalen.se and sort the data for further calculation. Results showed that there was a strong positive relationship between empirical estimated Biodiversity and BBCI. Again Shannon diversity index and BBCI also demonstrated a positive correlation between them. It showed BBCI could explain 60%-69% of species richness data and 17%-22% of Shannon diversity index. It indicates the acceptance of theoretical study of measure Biodiversity.

Le premier chapitre étudie comment l'introduction d'un marché à terme de l'acier affecte les producteurs d'acier et leurs clients. Le deuxième chapitre demande comment les tarifs d'importation dans les industries en amont affectent les incitations à investir des entreprises en aval. Le troisième chapitre étudie comment la propriété managériale affecte la performance dans le secteur des fonds communs de placement. / The first chapter studies how the introduction of a futures market for steel affects steel producers and their customers. The second chapter asks how import tariffs in upstream industries affect downstream firms’ incentives to invest. The third chapter studies how managerial ownership affects performance in the mutual fund industry.

Mid-level leaders are often expected to implement employee empowerment initiatives, yet many do not have a clear understanding of how to empower employees. To address this issue, a model of empowering leadership was developed. The model presents specific, actionable behaviors that a leader should perform in order to empower employees. The model comprises 13 factors built around the areas of ability, accountability, and authority. First, leaders must ensure employees have the ability to be empowered. To do so, they must (a) build employee organizational knowledge, (b) provide access to pertinent information, (c) assure employees have the necessary skill set, and (d) identify and provide needed resources. Second, leaders must create systems of accountability for employee outcomes by (e) setting a standard of continuous improvement, (f) recognizing and rewarding good work, (g) regularly evaluating employee efforts, and (h) providing continuous feedback on employee efforts. Third, leaders should provide employees with the authority to be empowered by (i) serving as advocates of employee efforts, (j) providing an environment that is conducive to empowerment, (k) setting a clear and consistent direction to guide employee efforts, and (l) building systems and structures to support employee empowerment. The thirteenth factor of the model is a constant focus on the work, because without the work there is no real reason for empowerment. A review of the existing literature suggests a need for empirical research on empowerment concepts. This dissertation empirically investigated empowering leadership with two studies. The first focused on development of measures, while the second focused on model development. The measurement study supported the three general areas of ability, accountability, and authority, although the accountability area was weak. Results of the model examination study indicated that the model largely behaved as expected, but did require some modification. Based on the model exploration, four of the original 13 dimensions (set a standard of continuous improvement, provide continuous feedback on employee efforts, set a clear and consistent direction to guide employee efforts, and focus on work) were removed. Finally, the study revealed that a relationship does exist between employee empowerment and empowering leadership.

No description available.

Cascading Style Sheets (CSS) has become essential to front-end web development for the specification of style. But despite its simple syntax and the theoretical advantages attained through the separation of style from content and behavior, CSS authoring today is regarded as a complex task. As a result, developers are increasingly turning to CSS preprocessor languages and web frameworks to aid in development. However, previous studies show that even highly popular websites which are known to be developed with web frameworks contain CSS code smells such as duplicated rules and hard-coded values. Such code smells have the potential to cause adverse effects on websites and complicate maintenance. It is therefore important to investigate whether web frameworks may be encouraging the introduction of CSS code smells into websites. In this thesis, we investigate the prevalence of CSS code smells in websites built with different web frameworks and attempt to recognize a pattern of CSS behavior in these frameworks. We collect a dataset of several hundred websites produced by each of 19 different frameworks, collect code smells and other metrics present in the CSS code of each website, train a classifier to predict which framework the website was built with, and perform various clustering tasks to gain insight into the correlations between code smells. Our results show that CSS code smells are highly prevalent in websites built with web frameworks, we achieve an accuracy of 39% in correctly classifying the frameworks based on CSS code smells and metrics, and we find interesting correlations between code smells.

This dissertation consists of three chapters exploring education and crime in the modern economy. The first two chapters focus on inter-district school choice and teacher labor markets in Massachusetts. The third chapter examines the demolition of public housing in Chicago and its interaction with the geospatial distribution of gang territory. In the first chapter, I study the sorting of students to school districts using new lottery data from an inter-district school choice program. I find that moving to a more preferred school district generates benefits to student test scores, coursework quality, high-school graduation, and college attendance. Motivated by these findings, I develop a rich model of treatment effect heterogeneity and estimate it using a new empirical-Bayes-type procedure that leverages non-experimental data to increase precision in quasi-experimental designs. I use the heterogeneous effects to show that nearly all the test score gains from the choice program emerge from Roy selection. In the second chapter (joint with Scott Imberman and Marcus Winters), we describe the relationship between school quality, teacher value-added, and teacher attrition across the public and charter sectors. We begin by documenting important differences in the sources of variation that explain attrition across sectors. Next we demonstrate that while charters are in fact more likely to remove their worst teachers, they are also more likely to lose their best. We conclude by exploring the type and quality of destination schools among teachers who move. In the third chapter, I study the demolition of 22,000 units of public housing on crime in Chicago. Point estimates that incorporate both the direct and spillover effects indicate that in the short run, the average demolition increased city-wide crime by 0.5% per month relative to baseline, with no evidence of offsetting long run reductions. I also provide evidence that spillovers are mediated by demolition-induced migration across gang territorial boundaries. I reconcile my findings with contradictory results from the existing literature by proposing and applying a test for control group contamination. I find that existing results are likely biased by previously unaccounted for spillovers.

No description available.