Interval-censored data with misclassification: a Bayesian approach

Survival data involving silent events are often subject to interval censoring (the event is known to occur within a time interval) and classification errors if a test with no perfect sensitivity and specificity is applied. Considering the nature of this data plays an important role in estimating the time distribution until the occurrence of the event. In this context, we incorporate validation subsets into the parametric proportional hazard model, and show that this additional data, combined with Bayesian inference, compensate the lack of knowledge about test sensitivity and specificity improving the parameter estimates. The proposed model is evaluated through simulation studies, and Bayesian analysis is conducted within a Gibbs sampling procedure. The posterior estimates obtained under validation subset models present lower bias and standard deviation compared to the scenario with no validation subset or the model that assumes perfect sensitivity and specificity. Finally, we illustrate the usefulness of the new methodology with an analysis of real data about HIV acquisition in female sex workers that have been discussed in the literature.     

Carers and Professionals' Perspectives on Foster Care Outcomes: The Role of Contact

This study investigates the association between the contact of children or young people in care with their family, and the foster care placement evaluation (positive or negative) in Portugal. According to the perspectives of foster carers and service professionals' perceptions regarding children and young people's reactions, during and after the visits, are measured. Utilizing a quantitative approach, two fostering services teams and 140 foster carers completed questionnaires, which had 212 children in common. Results indicated that despite the importance of continued contact, especially for children and their parents, it was not determined to be essential to long-term placement. On one hand, there was the perception that a high percentage of children expressed positive reactions during and after the visit, while on the other hand, this didn't influence the perception of placement success. This study also showed significant differences between foster carers' and the professionals' perceptions on several dimensions of foster care, especially the children's reactions during visits. These differences need to be further analyzed in future research and the outcomes used to help improve contact management.     

Quality of life and sustainability issues as seen by the population of low-income housing in the region of Campinas, Brazil

This paper presents a study on quality of life and sustainability indicators relating to site-planning parameters for low-income public housing projects in the region of Campinas, Brazil. The study is based on a post-occupancy-evaluation (POE), conducted in five housing developments. Most of these housing projects are based on a repetitive model and are devoid of urban infrastructure. Users act on their own in providing for some elements considered necessary to create an identity and community spirit. Results show that the population relates quality of life to economic factors and sustainability is associated to reduce utility bills. Houses are preferred to apartments and satisfaction with the present housing conditions is high, despite low feelings of security in the neighbourhood. This work is part of a broader study, which aims to develop design evaluation tools. Most sensitive quality of life and sustainability indicators related to site-planning should permeate these tools and establish design guidelines. The inclusion of a large number of qualitative design issues into the decision-making process and the questioning of existing standardized solutions are seen as essential means to increase local housing quality.     

Violence in the Brazilian favelas and the role of the police

Institutions should normally have an integrative influence. The family, for example, has the task of protecting and giving socio-emotional support to children, and schools should prepare young people for their future. Ideally the common goal of all of society's institutions is to secure the integration of youth and prevent or intervene against deviant behavior. But sometimes institutions provoke or even cause juvenile delinquency. The article discusses institutional influences and the role of the police in the criminal and violent situation in the favelas of Rio de Janeiro.Starting with an overview of the origins and the development of violence, crime, and drug trafficking in the favelas, the authors show how these slums arose. Their analysis examines the lack of a state presence with an integration policy to avoid social disintegration. Instead of social integration policy, there is a dual approach that both controls and produces violence. The article also presents the first results of a government attempt in 2000 to introduce a new police unit to stop the violence and improve the social opportunity structure of the residents of the favelas, especially young people.     

A generalization of the Solis-Wets method

In this paper we focus on the application of global stochastic optimization methods to extremum estimators. We propose a general stochastic method—the master method—which includes several stochastic optimization algorithms as a particular case. The proposed method is sufficiently general to include the Solis-Wets method, the improving hit-and-run algorithm, and a stochastic version of the zigzag algorithm. A matrix formulation of the master method is presented and some specific results are given for the stochastic zigzag algorithm. Convergence of the proposed method is established under a mild set of conditions, and a simple regression model is used to illustrate the method.     

Work-to-Family Enrichment and Employees’ Well-Being: High Performance Work System and Job Characteristics

Research has demonstrated the importance of job characteristics to explain work-to-family enrichment (WFE) and the value of this enrichment to explain employees’ wellbeing. However, there is no comprehensive framework to explain the relationship between these variables. This study uses the Job Demands-Control-Support model as a guiding framework, and examines the relationship between these job characteristics and WFE and, more interestingly, the WFE as a mechanism for explaining the relationship between job characteristics and employees’ well-being. Furthermore, we analyzed the relationship of employees’ perceptions of High Performance Work System (HPWS) with job characteristics. With a sample of 1,390 employees from a Portuguese bank, job demands were found to be negatively related to WFE while autonomy and supervisor support displayed a positive relation. We also observed that WFE is an important mechanism to explain the relationship between these job characteristics and employees’ well being. As expected, HPWS was a relevant organizational characteristic to explain job characteristics, however, we observed that it was also directly related to WFE.     

Smoking Risks in Spain: Part I—Perception of Risks to the Smoker

Survey evidence for the Spanish population indicates that perceptions of lung cancer risk and life expectancy loss due to smoking are similar to estimates found in the United States. This paper also presents new evidence on the relative lung cancer risk for smokers, the perceived risk of lung disease for smokers, the heart disease risk for smokers, and the relative heart disease risk for smokers, all of which indicate substantial risk perceptions. Risk beliefs are particularly high for younger respondents, but are lower for better educated respondents.     

Model comparison for a complex ecological system

Summary.  The ecological consequences of climate change and its interaction with other environmental pressures, such as nutrient pollution, are little understood. For freshwater ecosystems, knowledge of these combined effects is required for water resource management and in particular for successful implementation of the European Community Water Framework Directive 2000, which requires that all surface-waters should be at, or above, 'good status' by 2016. Statistical analysis of detailed long-term environmental data sets can be used to explore these combined effects. Loch Leven (Scotland) has been routinely monitored since 1967, providing one of the largest and most extensive of such data sets. Over this period there has been evidence of climate change and a period of eutrophication and recovery at the loch. Transfer functions, additive models and varying-coefficient models are used to explore the complex ecological system at Loch Leven with the aim of obtaining insight into the combined effects of climate change and eutrophication on water quality.     

Factor stochastic volatility with time varying loadings and Markov switching regimes

We generalize the factor stochastic volatility (FSV) model of Pitt and Shephard [1999. Time varying covariances: a factor stochastic volatility approach (with discussion). In: Bernardo, J.M., Berger, J.O., Dawid, A.P., Smith, A.F.M. (Eds.), Bayesian Statistics, vol. 6, Oxford University Press, London, pp. 547–570.] and Aguilar and West [2000. Bayesian dynamic factor models and variance matrix discounting for portfolio allocation. J. Business Econom. Statist. 18, 338–357.] in two important directions. First, we make the FSV model more flexible and able to capture more general time-varying variance–covariance structures by letting the matrix of factor loadings to be time dependent. Secondly, we entertain FSV models with jumps in the common factors volatilities through So, Lam and Li's [1998. A stochastic volatility model with Markov switching. J. Business Econom. Statist. 16, 244–253.] Markov switching stochastic volatility model. Novel Markov Chain Monte Carlo algorithms are derived for both classes of models. We apply our methodology to two illustrative situations: daily exchange rate returns [Aguilar, O., West, M., 2000. Bayesian dynamic factor models and variance matrix discounting for portfolio allocation. J. Business Econom. Statist. 18, 338–357.] and Latin American stock returns [Lopes, H.F., Migon, H.S., 2002. Comovements and contagion in emergent markets: stock indexes volatilities. In: Gatsonis, C., Kass, R.E., Carriquiry, A.L., Gelman, A., Verdinelli, I. Pauler, D., Higdon, D. (Eds.), Case Studies in Bayesian Statistics, vol. 6, pp. 287–302].     

Connectivity and Resilience: A Multidimensional Analysis of Infrastructure Impacts in the Southwestern Amazon

Infrastructure is a worldwide policy priority for national development via regional integration into the global economy. However, economic, ecological and social research draws contrasting conclusions about the consequences of infrastructure. We present a synthetic approach to the study of infrastructure, focusing on a multidimensional treatment of indicators of connectivity and resilience. As our study case, we adopt a tri-national frontier in the southwestern Amazon being integrated by a highway, and use survey data for rural leaders to evaluate the relationship of community connectivity to market towns and social-ecological resilience. The findings show varying relationships among different dimensions of connectivity and resilience, which bear implications regarding indicator approaches to the study of infrastructure impacts.