A generalization of the compound rayleigh distribution: using a bayesian method on cancer survival times

In this paper the generalized compound Rayleigh model, exhibiting flexible hazard rate, is high¬lighted. This makes it attractive for modelling survival times of patients showing characteristics of a random hazard rate. The Bayes estimators are derived for the parameters of this model and some survival time parameters from a right censored sample. This is done with respect to conjugate and discrete priors on the parameters of this model, under the squared error loss function, Varian's asymmetric linear-exponential (linex) loss function and a weighted linex loss function. The future survival time of a patient is estimated under these loss functions. A Monte Carlo simu¬lation procedure is used where closed form expressions of the estimators cannot be obtained. An example illustrates the proposed estimators for this model.     

A generalized multivariate beta distribution: control charting when the measurements are from an exponential distribution

In Statistical Process Control (SPC) there exists a need to model the run-length distribution of a Q-chart that monitors the process mean when measurements are from an exponential distribution with an unknown parameter. To develop exact expressions for the probabilities of run-lengths the joint distribution of the charting statistics is needed. This gives rise to a new distribution that can be regarded as a generalized multivariate beta distribution. An overview of the problem statement as identified in the field of SPC is given and the newly developed generalized multivariate beta distribution is proposed. Statistical properties of this distribution are studied and the effect of the parameters of this generalized multivariate beta distribution on the correlation between two variables is also discussed.     

Childcare involvement, job characteristics, gender and work attitudes as predictors of emotional exhaustion and sickness absence

Reports in the literature vary regarding the existence of gender differences in relation to burnout and sickness absence. To investigate this, the present study was aimed at investigating the role of several gender-relevant variables, particularly childcare obligations, job characteristics, and work attitudes in emotional exhaustion and sickness absence in 404 male and female nurses in an institution for people with learning difficulties. Questionnaires were administered reflecting demographic and job characteristics, work and non-work attitudes, and emotional exhaustion (as measured by the Emotional Exhaustion Scale of the Maslach Burnout Inventory). Female nurses were expected to report higher levels of emotional exhaustion and to be absent through sickness more often than men. Also, childcare investment, job characteristics, and (non) work attitudes were expected—via emotional exhaustion—to predict gender differences in sickness absence. It was found that women did not have higher sickness absence rates, and although a gender difference appeared in emotional exhaustion it was in the opposite direction from that predicted. For both genders, emotional exhaustion had a significant positive effect on sickness absence, and especially childcare investment and number of work hours appeared to contribute to both outcomes. These results are of interest because, despite current stereotypes, sickness absence was not higher in women, and neither were women more at risk for emotional exhaustion. In particular, load—workload as well as care load—appeared to predict emotional exhaustion and thus sickness absence.     

Transient analysis of one-sided Lévy-driven queues

In this article, we analyze the transient behavior of the workload process in a Lévy-driven queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of spectrally one-sided Lévy input processes, for which we succeed in deriving explicit results. As an application, we approximate the mean and the Laplace transform of the workload process after a deterministic time.     

The type I distribution of the ratio of independent “Weibullized” generalized beta-prime variables

In this paper we introduce the distribution of , with c >  0, where X _i , i =  1, 2, are independent generalized beta-prime-distributed random variables, and establish a closed form expression of its density. This distribution has as its limiting case the generalized beta type I distribution recently introduced by Nadarajah and Kotz (2004). Due to the presence of several parameters the density can take a wide variety of shapes.      

Preliminary test and Bayes Estimation of a Location Parameter Under Blinex Loss

In this article, the preliminary test estimator is considered under the BLINEX loss function. The problem under consideration is the estimation of the location parameter from a normal distribution. The risk under the null hypothesis for the preliminary test estimator, the exact risk function for restricted maximum likelihood and approximated risk function for the unrestricted maximum likelihood estimator, are derived under BLINEX loss and the different risk structures are compared to one another both analytically and computationally. As a motivation on the use of BLINEX rather than LINEX, the risk for the preliminary test estimator under BLINEX loss is compared to the risk of the preliminary test estimator under LINEX loss and it is shown that the LINEX expected loss is higher than BLINEX expected loss. Furthermore, two feasible Bayes estimators are derived under BLINEX loss, and a feasible Bayes preliminary test estimator is defined and compared to the classical preliminary test estimator.     

On the Bivariate Kummer-Beta Type IV Distribution

Recent studies have shown the X-bar control chart with variable sampling interval detects shifts in the process mean faster than the traditional X-bar chart. These studies are usually based on the assumption that the process data are independently and normally distributed. However, many situations in practice violate these assumptions. In this study, a methodology is developed to economically design a variable sampling interval X-bar control chart that takes into consideration correlated non normal sample data. An example is provided to illustrate the solution procedure. A sensitivity analysis on the input parameters (i.e., the cost and the process parameters) is performed taking into account the non normality and the correlation on the optimal design of the chart.     

Achieving the Optimal Vaginal State: Using Vaginal Products and Study Gels in Uganda,Zimbabwe, and South Africa

Preferences and practices related to the vaginal condition have implications for the use of vaginal HIV prevention products. The authors used qualitative methods to explore narratives relating to the vaginal state amongst women in South Africa, Uganda, and Zimbabwe who had previously participated in a biomedical HIV prevention trial. They investigated women's behaviors related to optimizing the vaginal state, experiences and perceptions of the gel's effect on the vaginal state and on penile-vaginal intercourse, women's narratives on male partner perceptions, and how preferences relating to the vaginal state may have interfered with gel use.     

A shift in Western development agency thinking? The case for second best

This review essay illustrates a turn in Western development agency thinking in two recent publications intended for development agencies and African “reformers,” by authors with long careers in Western development institutions. Both publications explicitly reject – at least for the short to medium term – a comprehensive “good governance” approach to development. Subsequently, a publication entitled Violence and Social Orders, authored by three American scholars with an interest in the role of institutions in historical change, is reviewed since it is a crucial influence in the consolidation of this turn in thinking. This new Western approach is more restrained in its ambition to introduce new governance institutions in the developing world. This implies that it is prepared to tolerate what it considers to be imperfections in both the state and the market, viewing these as a second best result (in the short to medium term) in exchange for greater chances of realising positive development outcomes over the long term.     

Preliminary testing of the Cobb–Douglas production function and related inferential issues

In this article, we consider the multiple regression model in the presence of multicollinearity and study the performance of the preliminary test estimator (PTE) both analytically and computationally, when it is a priori suspected that some constraints may hold on the vector parameter space. The performance of the PTE is further analyzed by comparing the risk of some well-known estimators of the ridge parameter through an extensive Monte Carlo simulation study under some bounded and or asymmetric loss functions. An application of the Cobb–Douglas production function is included and from these results as well as the simulation studies, it is clear that the bounded linear exponential loss function outperforms the other loss functions across all the proposed ridge parameters by comparing the risk values.