Testing inference in heteroskedastic linear regressions: a comparison of two alternative approaches

We consider the issue of performing testing inferences on the parameters that index the linear regression model under heteroskedasticity of unknown form. Quasi-t test statistics use asymptotically correct standard errors obtained from heteroskedasticity-consistent covariance matrix estimators. An alternative approach involves making an assumption about the functional form of the response variances and jointly modelling mean and dispersion effects. In this paper we compare the accuracy of testing inferences made using the two approaches. We consider several different quasi-t tests and also z tests performed after estimated generalized least squares estimation which was carried out using three different estimation strategies. The numerical evidence shows that some quasi-t tests are typically considerably less size distorted in small samples than the tests carried out after the jointly modelling of mean and dispersion effects. Finally, we present and discuss two empirical applications.     

Analysis of the Better Life Index Trough a Cluster Algorithm

Social Indicators Research - This paper discusses some concepts attributed to the term well-being and different ways to measure it. Then we present an alternative approach based on clustering...     

Use of exponential power distributions for mixture models in the presence of covariates

In this paper, we present a Bayesian analysis of exponential power mixture models in the presence of a covariate. Considering Gibbs sampling with MetropolisHastings algorithms, we obtain Monte Carlo estimates for the posterior quantities of interest.     

An Intertemporal Analysis of Development Policies in the EU

In this paper, we focus on the effects of EU structural transfer programs on the evolution of the EU less developed economies. We develop a two-sector endogenous growth model of private and public physical capital and human capital accumulation in which the public sector and the current account balances play a crucial role. This model is applied to Portugal. Simulation results suggest that structural programs will bring Portuguese GDP per capita to 63.7% of the EU average (up from around 54% in the last two decades), thereby greatly contributing to the process of real convergence of the Portuguese economy to EU standards. Additional transfers, primarily targeted at infrastructure development, are necessary, however, if a greater degree of real convergence is to be achieved. Furthermore, the impact of transfers on public deficits, the current account, and real exchange rates might adversely affect the long run requirements of nominal convergence and might exacerbate the need for budgetary restraint in Portugal. Accordingly, a relaxation of domestic matching fund requirements might be desirable.     

Manual bamboo cutting tool

The paper presents the development of a cutting tool guide, specifically for the harvest of bamboo. The development was made based on precepts of eco-design and ergonomics, for prioritizing the physical health of the operator and the maintenance of the environment, as well as meet specific requirements of bamboo. The main goal is to spread the use of bamboo as construction material, handicrafts, among others, from a handy, easy assembly and material available tool.     

Is there enough information to calculate the financial benefits of ergonomics projects?

Many authors studied work situations and, mainly, ergonomics projects concerning the financial benefit point of view. At the same time seems to be little information available concerning these financial benefits in manufacturing companies' processes. The aim of this article is to identify if there enough information available within a company to quantify the financial benefits of an ergonomic project. The study was applied on two manufacturing companies, one in Brazil and other in Portugal. A literature review based checklist and a manager interview was applied on each company in order to identify if the information was available and how were been used. The two companies have revealed a good quantity of available information regarding ergonomics benefit calculation. The interviews showed that managers are not aware of the financial savings possibility with investments in ergonomics projects.     

Nachhaltige Stressreduktion durch Introvision: theoretische Grundlagen und empirische Ergebnisse

The article deals with a re-analysis of two studies in which the pedagogical-psychological counseling and coaching method Introvision as method of reducing somatic symptoms (tinnitus, neck strain) and in particular the so resulting stress was tested. It based on the transactional stress model and the theory of mental Introferenz is a connection between consciousness and the emergence of conflicts of stress, as well as its specific somatic effects is produced. Subsequently, the data of both experimental and control groups are compared and brought into relation. In particular, three aspects are considered: the extent of exposure (as measured by the GSI and the TICS) between the study groups (tinnitus, neck strain), the development of the different study groups (tinnitus, neck strain) over time (pre, post, follow-up ) and possible similarities. On the one hand it can be said that comparable on a theoretical level in coping with stressful events in the sense of conflict avoidance strategies, the Introvision is however used as a conflict resolution strategy, and thus provides a means for the alternative stress management. The study groups differed in their baseline levels of both the normal population and from each other (in some cases significantly). Both study groups improved significantly compared to the control group, and have a similar profile. Especially in the initial values for the stress they are different, which suggests that tinnitus sufferers use different coping strategies (dramatized) (minimize) as concerned with neck tension. The Introvision proves consulting and coaching method for reducing the burden of somatic complaints and stress, as well as prevention methods, ie the further deterioration of symptoms (compared to the control group), one advancing chronicity process works effectively.