Tempered stable Ornstein– Uhlenbeck processes: A practical view

We study the one-dimensional Ornstein–Uhlenbeck (OU) processes with marginal law given by tempered stable and tempered infinitely divisible distributions. We investigate the transition law between consecutive observations of these processes and evaluate the characteristic function of integrated tempered OU processes with a view toward practical applications. We then analyze how to draw a random sample from this class of processes by considering both the classical inverse transform algorithm and an acceptance–rejection method based on simulating a stable random sample. Using a maximum likelihood estimation method based on the fast Fourier transform, we empirically assess the simulation algorithm performance.     

White historical activity theory: toward a critical understanding of white zones of proximal development

Best known for arguing that individual development is part of social and historical development Vygotsky’s entry into education may be captured by his concept of the ‘zone of proximal development’ (ZPD). ZPD has not yet been synthesized with a critical study of whiteness. When ZPD is used to explain racial disparities in the service of inclusion, it is usually connected with the lives of people of color. This leaves out a critical understanding of racially dominant experiences, or whiteness. This article argues that a progressive union between Vygotsky and the field of race studies generally, Whiteness Studies specifically, benefits educators insofar as the concept of ZPD is applied to the particular ideological development of white identity. Likewise, Whiteness Studies gains an explanatory framework to account for the cognitive development of the dominant racial group, in short, a learning theory of whiteness. A Whiteness Studies intervention within Vygotskian theory pushes the limits of developmental theory when it analyzes the contours of a white ZPD. When racialized to consider whiteness, certain terms and concepts, such as Vygotsky’s genotypic and phenotypic analyses, take on a different significance, even different meanings. As a racially sensitive framework, particularly within a US-based understanding, Vygotskian theory is limited without critical attention to the development of white identity and whiteness as an ideology. By focusing on this nexus, Vygotskian theory fulfills part of its historical mission as a concrete study of cultural relations.     

Do Marginal Employment Subsidies Increase Re-Employment Probabilities? Preliminary Results on the Experiment of the Agenzia del Lavoro of Trento (Italy)

ABSTRACT: The purpose of this paper is to test whether a Marginal Employment Subsidy program (MES) is effective in reducing the length of unemployment spells. Our test is constructed in such a way as to isolate the direct effect of the MES from the business cycle effect (i.e. the variation in unemployment that would have normally occurred in the absence of the program). Specifically, we estimate a Markov chain duration model with time-varying covariates and we test if eligibility for an MES increases the hazard rate of leaving unemployment. One of the time-varying covariates is an index of macro-economic performance that controls for the variation in the hazard rate due to business cycle fluctuations. The net effect of the MES offered by the Agenzia del Lavoro of Trento, Italy, is shown to be significantly positive: the Marginal Employment Subsidy program increases the re-employment probability and reduces the expected duration of unemployment by twenty one months.     

When money does not buy happiness: The case of “frustrated achievers”

An increase in real per capita income is generally expected to be associated with nonnegative variations in life satisfaction. The alternative (association with negative changes) is generally defined as “frustrated achievement” [Graham, C., Pettinato, S., 2002. Happiness and Hardship: Opportunity and Insecurity in New Market Economies. The Brookings Institution Press, Washington, D.C.].We investigate the determinants of “frustrated achievement” in the German socioeconomic panel on more than 30,000 individuals collected between 1992 and 2004. We observe a parallel reduction in self-declared life satisfaction corresponding to almost one-third of yearly increases in (equalised) real household income.Our econometric findings show that the lack of a full-time job, health deterioration, relative income effects, marital status shocks and poorer social life are the main factors associated with this phenomenon.     

Ergonomics, automation and logistics: practical and effective combination of working methods, a case study of a baking company

The aim of this study was to combine three different analytical methods from three different disciplines to diagnose the ergonomic conditions, manufacturing and supply chain operation of a baking company. The study explores a summary of comprehensive working methods that combines the ergonomics, automation and logistics study methods in the diagnosis of working conditions and productivity. The participatory approach of this type of study that involves the feelings and first-hand knowledge of workers of the operation are determining factors in defining points of action and ergonomic interventions, as well as defining opportunities in the automation of manufacturing and logistics, to cope with the needs of the company. The study identified an ergonomic situation (high prevalence of wrist-hand pain), and the combination of interdisciplinary techniques applied allowed to improve this condition in the company. This type of study allows a primary basis of the opportunities presented by the combination of specialized methods of different disciplines, for the definition of comprehensive action plans for the company. Additionally, it outlines opportunities for improvement and recommendations to mitigate the burden associated with occupational diseases and as an end result improve the quality of life and productivity of workers.     

Dynamic survival models with spatial frailty

In many survival studies, covariates effects are time-varying and there is presence of spatial effects. Dynamic models can be used to cope with the variations of the effects and spatial components are introduced to handle spatial variation. This paper proposes a methodology to simultaneously introduce these components into the model. A number of specifications for the spatial components are considered. Estimation is performed via a Bayesian approach through Markov chain Monte Carlo methods. Models are compared to assess relevance of their components. Analysis of a real data set is performed, showing the relevance of both time-varying covariate effects and spatial components. Extensions to the methodology are proposed along with concluding remarks.     

Predicting probabilities for the 2010 FIFA World Cup games using a Poisson-Gamma model

In this paper, we provide probabilistic predictions for soccer games of the 2010 FIFA World Cup modelling the number of goals scored in a game by each team. We use a Poisson distribution for the number of goals for each team in a game, where the scoring rate is considered unknown. We use a Gamma distribution for the scoring rate and the Gamma parameters are chosen using historical data and difference among teams defined by a strength factor for each team. The strength factor is a measure of discrimination among the national teams obtained from their memberships to fuzzy clusters. The clusters are obtained with the use of the Fuzzy C-means algorithm applied to a vector of variables, most of them available on the official FIFA website. Static and dynamic models were used to predict the World Cup outcomes and the performance of our predictions was evaluated using two comparison methods.     

Comments on “Sums,Products, and Ratios of Non-Central Beta Variables” by Saralees Nadarajah

Brief comments on “Sums, Products, and Ratios of Non-Central Beta Variables” by Saralees Nadarajah, which appeared in Communications in Statistics – Theory and Methods, Volume 34, Issue 1, pp. 89–100.     

Food Aid in Complex Emergencies: Lessons from Sudan

The term "complex emergency" was coined by the UN to imply a phenomenon characterized by a combination of causes (conflicts, war, famine, displacement) requiring a combination of responses (military, peacekeeping, relief ). The "complexity" refers to the "multi–mandate" nature of the response as well as the multi–causal nature of the emergency. Operation Lifeline Sudan (OLS), the UN humanitarian assistance programme in Sudan, has been described as history's largest humanitarian intervention in an active civil war, providing a model for the international community in what can be achieved in complex political emergencies. The paper reviews how humanitarian aid was used in Sudan, and the potential for that usage contributing to development. The political dimension of decisions taken and implemented by donors, the United Nations and non–governmental organizations is explored.