A new generalization of skew-T distribution with volatility models

In this paper, we propose a new generalized alpha-skew-T (GAST) distribution for generalized autoregressive conditional heteroskedasticity (GARCH) models in modelling daily Value-at-Risk (VaR). Some mathematical properties of the proposed distribution are derived including density function, moments and stochastic representation. The maximum likelihood estimation method is discussed to estimate parameters via a simulation study. Then, the real data application on S&P-500 index is performed to investigate the performance of GARCH models specified under GAST innovation distribution with respect to normal, Student's-t and Skew-T models in terms of the VaR accuracy. Backtesting methodology is used to compare the out-of-sample performance of the VaR models. The results show that GARCH models with GAST innovation distribution outperforms among others and generates the most conservative VaR forecasts for all confidence levels and for both long and short positions.     

Association Between Unemployment Duration and Depression in the SouthWest Region of Turkey: A Cross-Sectional Study

ABSTRACT

Unemployment has risen as an effect of globalization in the country of Turkey. To date, no studies have examined the association between the duration of unemployment and perceived mental health. Therefore, the aim of this study is to evaluate the association between the duration of unemployment and the incidenence of depression among citizens in the southwest region of Turkey. A questionnaire was developed and distributed to 908 unemployed individuals. The questionnaire gathered sociodemographic characteristics and employment-related circumstances. To measure mental health, a depression inventory was administered and group-wise t-tests and logistic regressions were conducted. The findings show that long-term unemployed persons had more episodes of depressive moods in the past 12 months when compared with the group of the short-term unemployed. In addition, depression levels were higher among the long-term unemployed compared with the short-term unemployed. It was estimated that the duration of unemployment and the measurement of depression had a positive correlation. Risk factors that increased depression in the short-term unemployed were gender (female), older age, and greater periods of unemployment. However, higher education, income, and having social insurance significantly decreased the risk of developing depression for both the short-term and the long-term unemployed. Future recommendations include supportive counseling to increase motivation levels and developing strategies to handle periods of unemployment.     

The International from the perspectives of Gezi Protestors

Gezi Protests that started in Istanbul and spilled over to other cities in the Spring of 2013 has been regarded as an important episode of Turkish politics in the 21^st century. Although it happened in congruous with protests movements in different localities in the world as well as significant transformations in Turkey's foreign policy, the question of the influence of the international in these protests has been largely unexplored. This paper presents the empirical findings of a fieldwork on Gezi Protests, asking the following questions: What was the perception of the actors on the neighbouring as well as geographically distant uprisings that were congruous in time? How do they perceive the roles of domestic and international politics in shaping the agenda of their movements?     

A framework for production rescheduling in sociotechnical manufacturing environments

No plan survives contact with reality. Despite the rich research base regarding handling uncertainty in production planning and control systems, there is an intellectual gap between theory and practice with regard to handling unforeseen events generated by internal and external factors, such as unforeseen machine downtimes and changes in demand. Motivated by longitudinal observations in two industrial settings and an analysis of the relevant literature, a framework for rescheduling decision-making in the face of unforeseen production events is proposed. In practical settings, the effectiveness of decisions depends on a set of situational factors. The findings of this research can be utilised further to provide guidelines for developing effective decision support principles and systems, addressing the needs of organisational decision-makers.     

Value-at-risk estimation with new skew extension of generalized normal distribution

In this paper, we introduce a new distribution, called the alpha-skew generalized normal (ASGN), for GARCH models in modeling daily Value-at-Risk (VaR). Basic structural properties of the proposed distribution are derived including probability and cumulative density functions, moments and stochastic representation. The real data application based on ISE-100 index is given to show the performance of GARCH model specified under ASGN innovation distribution with respect to normal, Student’s-t, skew normal and generalized normal models in terms of the VaR accuracy. The empirical results show that GARCH model with ASGN innovation distribution generates the most accurate VaR forecasts for all confidence levels.     

Quasi local odds symmetry model for square contingency table with ordinal categories

This paper proposes a new model for square contingency tables. The proposed model tests the equality of local odds ratios between the one side of the main diagonal and corresponding other side and it represents the non-symmetric structure of the square contingency table. The proposed model is compared with twenty-five models introduced for analysing the square contingency tables for both symmetric and non-symmetric structures. The results show that the proposed model provides best fit performance than other existing models for square contingency tables.     

The generalized odd log-logistic family of distributions: properties,regression models and applications

We propose a new class of continuous distributions with two extra shape parameters named the generalized odd log-logistic family of distributions. The proposed family contains as special cases the proportional reversed hazard rate and odd log-logistic classes. Its density function can be expressed as a linear combination of exponentiated densities based on the same baseline distribution. Some of its mathematical properties including ordinary moments, quantile and generating functions, two entropy measures and order statistics are obtained. We derive a power series for the quantile function. We discuss the method of maximum likelihood to estimate the model parameters. We study the behaviour of the estimators by means of Monte Carlo simulations. We introduce the log-odd log-logistic Weibull regression model with censored data based on the odd log-logistic-Weibull distribution. The importance of the new family is illustrated using three real data sets. These applications indicate that this family can provide better fits than other well-known classes of distributions. The beauty and importance of the proposed family lies in its ability to model different types of real data.     

Voluntary leadership: motivation and influence

In social dilemmas, leading a team by making heroic efforts may prove costly, especially when the followers are not adequately motivated to make similar sacrifices. Attempting to shed light on what drives people to lead, we devise a two-stage public good experiment with endogenous timing. We show that leading by making generous contributions is widespread and relatively persistent. At least three motives explain this behavior. Some use leadership strategically to distill personal gains, with the expectation that others will respond by being at least as generous. Others are more altruistic, volunteering to lead even though this may come at a personal cost. Yet for another fraction of volunteers, a concern for maintaining a positive social image appears to be responsible. We also find that voluntary leaders are not necessarily more influential than randomly-chosen leaders.     

The odd power cauchy family of distributions: properties,regression models and applications

We study some mathematical properties of a new generator of continuous distributions with one extra parameter called the odd power Cauchy family including asymptotics, linear representation, moments, quantile and generating functions, entropies, order statistics and extreme values. We introduce two bivariate extensions of the new family. The maximum likelihood method is discussed to estimate the model parameters by means of a Monte Carlo simulation study. We define a new log-odd power Cauchy–Weibull regression model. The usefulness of the proposed models is proved empirically by means of three real data sets.