Bayesian robustness of the compound Poisson distribution under bidimensional prior: an application to the collective risk model

The distribution of the aggregate claims in one year plays an important role in Actuarial Statistics for computing, for example, insurance premiums when both the number and size of the claims must be implemented into the model. When the number of claims follows a Poisson distribution the aggregated distribution is called the compound Poisson distribution. In this article we assume that the claim size follows an exponential distribution and later we make an extensive study of this model by assuming a bidimensional prior distribution for the parameters of the Poisson and exponential distribution with marginal gamma. This study carries us to obtain expressions for net premiums, marginal and posterior distributions in terms of some well-known special functions used in statistics. Later, a Bayesian robustness study of this model is made. Bayesian robustness on bidimensional models was deeply treated in the 1990s, producing numerous results, but few applications dealing with this problem can be found in the literature.     

The generalized two-sided power distribution

The generalized standard two-sided power (GTSP) distribution was mentioned only in passing by Kotz and van Dorp Beyond Beta, Other Continuous Families of Distributions with Bounded Support and Applications, World Scientific Press, Singapore, 2004. In this paper, we shall further investigate this three-parameter distribution by presenting some novel properties and use its more general form to contrast the chronology of developments of various authors on the two-parameter TSP distribution since its initial introduction. GTSP distributions allow for J-shaped forms of its pdf, whereas TSP distributions are limited to U-shaped and unimodal forms. Hence, GTSP distributions possess the same three distributional shapes as the classical beta distributions. A novel method and algorithm for the indirect elicitation of the two-power parameters of the GTSP distribution is developed. We present a Project Evaluation Review Technique example that utilizes this algorithm and demonstrates the benefit of separate powers for the two branches of activity GTSP distributions for project completion time uncertainty estimation.     

Más allá de la sociología. Sobre catástrofes,expertos y comunidades

We could state that a catastrophic discourse is one that refers to a catastrophe which is avoided by the same discourse. This kind of discourse stimulates cautious behaviours. It is necessary that the actors do not know that the catastrophe exists and that they are avoiding it so that this situation can work. Nevertheless, the analyst knows everything. The catastrophic discourse takes part in a stable situation in which the analyst's knowledge is directly proportional to the actor alienation. The economist knows that unstable situations like panic produce an opposite phenomenon: the analyst does not know very well what is going on but the actor knows how to manage. If the market, as well as stable operation, permits instability, the prevention of catastrophes could admit an unstable one, similar to panic and together with the catastrophic solution. This paper suggests some concepts to think about this unstable and anticatastrophic situation. They are notions which give prominence to ‘emergentism’, autopoiesis and uncertainty. The reinterpretation of the Hobbesian natural state developed by Foucault, the analysis of the mobilization power of fear by Bataille and the unpolitical reflections of the community which have been proposed by Esposito, Nancy and Agamben will be reinterpreted in order to achieve this goal.     

Influence diagnostics in the capital asset pricing model under elliptical distributions

In this paper we consider the Capital Asset Pricing Model under Elliptical (symmetric) Distributions. This class of distributions, which contains the normal distribution, t, contaminated normal and power exponential, among others, offers a more flexible framework for modelling asset prices or returns. In order to analyze the sensibility to possible outliers and/or atypical returns of the maximum likelihood estimators, the local influence method was implemented. The results are illustrated by using a set of shares from companies who trade in the Chilean Stock Market. Our main conclusion is that symmetric distributions having heavier tails than those of the normal distribution, especially the t distribution with small degrees of freedom, show a better fit and allow the reduction of the influence of atypical returns in the maximum likelihood estimators.     

On the recoding of continuous and bounded indexes to a binomial form: an application to quality-of-life scores

The statistical analysis of patient-reported outcomes (PROs) as endpoints has shown to be of great practical relevance. The resulting scores or indexes from the questionnaires used to measure PROs could be treated as continuous or ordinal. The goal of this study is to propose and evaluate a recoding process of the scores, so that they can be treated as binomial outcomes and, therefore, analyzed using logistic regression with random effects. The general methodology of recoding is based on the observable values of the scores. In order to obtain an optimal recoding, the evaluation of the recoding method is tested for different values of the parameters of the binomial distribution and different probability distributions of the random effects. We illustrate, evaluate and validate the proposed method of recoding with the Short Form-36 (SF-36) Survey and real data. The optimal recoding approach is very useful and flexible. Moreover, it has a natural interpretation, not only for ordinal scores, but also for questionnaires with many dimensions and different profiles, where a common method of analysis is desired, such as the SF-36.     

Invisible or Mainstream? Disability in Surveys and Censuses in Low- and Middle-Income Countries

Social Indicators Research - This paper examines to what extent household surveys and censuses in low- and middle-income countries include disability questions and the types of questions under use....     

An empirical comparison of Canonical Correspondence Analysis and STATICO in the identification of spatio-temporal ecological relationships

The wide-ranging and rapidly evolving nature of ecological studies mean that it is not possible to cover all existing and emerging techniques for analyzing multivariate data. However, two important methods enticed many followers: the Canonical Correspondence Analysis (CCA) and the STATICO analysis. Despite the particular characteristics of each, they have similarities and differences, which when analyzed properly, can, together, provide important complementary results to those that are usually exploited by researchers. If on one hand, the use of CCA is completely generalized and implemented, solving many problems formulated by ecologists, on the other hand, this method has some weaknesses mainly caused by the imposition of the number of variables that is required to be applied (much higher in comparison with samples). Also, the STATICO method has no such restrictions, but requires that the number of variables (species or environment) is the same in each time or space. Yet, the STATICO method presents information that can be more detailed since it allows visualizing the variability within groups (either in time or space). In this study, the data needed for implementing these methods are sketched, as well as the comparison is made showing the advantages and disadvantages of each method. The treated ecological data are a sequence of pairs of ecological tables, where species abundances and environmental variables are measured at different, specified locations, over the course of time.     

Impact of funding and value added on Spanish venture capital-backed firms

This paper contributes to the literature on the effect of venture capital (VC) on the economic development of areas in which those specialized investors are active. The work focuses on the separate consideration of two effects that are supposed to explain the superior performance of a large sample of Spanish VC-backed firms, namely funding and value-added services provided by VC managers to their investee firms. The results show that funding is significant regardless of the stage of development of the investee firm. The value added, however, is only significant for the subsample of firms at the expansion stage.     

CHILD CARE AND POVERTY IN SOUTH AFRICA

This article draws on ethnographic research with children and their caregivers to explore the interaction between poverty and the nature and quality of child care in a resource-poor urban community in South Africa. The authors attend to issues such as mobility and “family fragmentation,” the role of the extended family and other networks, and children's contributions to their own and others’ care, all matters that provoke particular concern in the context of HIV/AIDS. The research challenges some of the more conventional interpretations on these matters by pointing to the continuities children experience in what can appear a disrupted care setting as well as the positive aspects of children's involvement in care. It also supports the case for a closer look at men's participation in various child-care roles in a climate where they are often dismissed as absent or unemployed and therefore non-contributory. Future research and policy on child care would benefit from the conceptual approach adopted across this work, which employs a relational lens and encompasses the dynamic contexts in which care is experienced and performed.