A class of correlated weighted Poisson processes

In this paper, we propose new classes of correlated Poisson processes and correlated weighted Poisson processes on the interval [0,1], which generalize the class of weighted Poisson processes defined by Balakrishnan and Kozubowski (2008), by incorporating a dependence structure between the standard uniform variables used in the construction. In this manner, we obtain another process that we refer to as correlated weighted Poisson process. Various properties of this process such as marginal and joint distributions, stationarity of the increments, moments, and the covariance function, are studied. The results are then illustrated through some examples, which include processes with length-biased Poisson, exponentially weighted Poisson, negative binomial, and COM-Poisson distributions.     

Ergonomic assessment among radiology technologists: a survey in a hospital

This article is the result of an Ergonomic Diagnosis in a study for a Specialization Course in Ergonomics. The research is being done in a public hospital in the city of Rio de Janeiro, where the target system is the radiology sector. For diagnosis purposes, subjective techniques were used, such as an open-ended survey, Corlett questionnaire and techniques for evaluating ergonomic risk such as Owas and Rula. Systematic observation was emphasized using photos and films. Preliminary observations made to the radiographers found that these professionals suffer risks of physical and verbal harassment, as well as sexual harassment. Most of them feel discriminated against in terms of race and accumulate activities demanding a lot of attention, as the medical diagnosis and subsequent procedures will depend on the outcome of this task. They accumulate tension due to the weight of responsibility, since there are cases where the patient has risk of death.     

Robert A. Stebbins: Arts Nonprofits: Associations and Agencies—A Literature Review

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -     

Career Maturity of Students in Accelerated Versus Traditional Programs

The authors assessed the career maturity of students in accelerated versus traditional academic programs. Students in traditional programs were hypothesized to be more advanced regarding their career decision making and development when compared with students in accelerated programs. The Medical Career Development Inventory (see M. L. Savickas, 1984) was administered to 441 medical students. Results showed that students in traditional programs had significantly greater career crystallization and career specification. Interventions are needed to further the career maturity and developmental tasks of students in accelerated programs.     

A frailty modeling approach for parental effects in animal breeding

Survival models involving frailties are commonly applied in studies where correlated event time data arise due to natural or artificial clustering. In this paper we present an application of such models in the animal breeding field. Specifically, a mixed survival model with a multivariate correlated frailty term is proposed for the analysis of data from over 3611 Brazilian Nellore cattle. The primary aim is to evaluate parental genetic effects on the trait length in days that their progeny need to gain a commercially specified standard weight gain. This trait is not measured directly but can be estimated from growth data. Results point to the importance of genetic effects and suggest that these models constitute a valuable data analysis tool for beef cattle breeding.     

EM algorithm-based likelihood estimation for a generalized Gompertz regression model in presence of survival data with long-term survivors: an application to uterine cervical cancer data

In this paper we develop a regression model for survival data in the presence of long-term survivors based on the generalized Gompertz distribution introduced by El-Gohary et al. [The generalized Gompertz distribution. Appl Math Model. 2013;37:13–24] in a defective version. This model includes as special case the Gompertz cure rate model proposed by Gieser et al. [Modelling cure rates using the Gompertz model with covariate information. Stat Med. 1998;17:831–839]. Next, an expectation maximization algorithm is then developed for determining the maximum likelihood estimates (MLEs) of the parameters of the model. In addition, we discuss the construction of confidence intervals for the parameters using the asymptotic distributions of the MLEs and the parametric bootstrap method, and assess their performance through a Monte Carlo simulation study. Finally, the proposed methodology was applied to a database on uterine cervical cancer.     

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.