Social Entrepreneur: Same or Different from the Rest?

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - A social business responds to social problems usually ignored by institutions, mobilizing resources and generating...     

Survival and lifetime data analysis with a flexible class of distributions

We introduce a general class of continuous univariate distributions with positive support obtained by transforming the class of two-piece distributions. We show that this class of distributions is very flexible, easy to implement, and contains members that can capture different tail behaviours and shapes, producing also a variety of hazard functions. The proposed distributions represent a flexible alternative to the classical choices such as the log-normal, Gamma, and Weibull distributions. We investigate empirically the inferential properties of the proposed models through an extensive simulation study. We present some applications using real data in the contexts of time-to-event and accelerated failure time models. In the second kind of applications, we explore the use of these models in the estimation of the distribution of the individual remaining life.     

Flexible objective Bayesian linear regression with applications in survival analysis

We study objective Bayesian inference for linear regression models with residual errors distributed according to the class of two-piece scale mixtures of normal distributions. These models allow for capturing departures from the usual assumption of normality of the errors in terms of heavy tails, asymmetry, and certain types of heteroscedasticity. We propose a general non-informative, scale-invariant, prior structure and provide sufficient conditions for the propriety of the posterior distribution of the model parameters, which cover cases when the response variables are censored. These results allow us to apply the proposed models in the context of survival analysis. This paper represents an extension to the Bayesian framework of the models proposed in [16]. We present a simulation study that shows good frequentist properties of the posterior credible intervals as well as point estimators associated to the proposed priors. We illustrate the performance of these models with real data in the context of survival analysis of cancer patients.     

REGULATING WORKERS COMPENSATION: THE MEDICO LEGAL EVALUATION OF INJURED WORKERS IN VICTORIA

Sociological research on occupational injury has been dominated by perspectives from the social organisation of work and the labour process. What is missing from this literature is an explanation of the actual experiences at the individual worker within the processes of legitimation of occupational injury. This study explores the experiences of injured workers as they move through the medico-legal process. Medical reports and clients perspectives were used to expose the positions of doctors, insurance companies, lawyers and workers compensation bureaucrats as they form a complex intersection of power and interest in the regulation of injured workers. In particular, the conflicting roles of doctors as both gatekeepers and service providers were highlighted in the maintenance of stigmatised damaged workers.     

On the existence of a normal approximation to the distribution of the ratio of two independent normal random variables

The distribution of the ratio of two independent normal random variables X and Y is heavy tailed and has no moments. The shape of its density can be unimodal, bimodal, symmetric, asymmetric, and/or even similar to a normal distribution close to its mode. To our knowledge, conditions for a reasonable normal approximation to the distribution of Z = X/Y have been presented in scientific literature only through simulations and empirical results. A proof of the existence of a proposed normal approximation to the distribution of Z, in an interval I centered at β = E(X) /E(Y), is given here for the case where both X and Y are independent, have positive means, and their coefficients of variation fulfill some conditions. In addition, a graphical informative way of assessing the closeness of the distribution of a particular ratio X/Y to the proposed normal approximation is suggested by means of a receiver operating characteristic (ROC) curve.     

A note on the moments of stochastic shrinkage parameters in ridge regression

The purpose of this note is to gain insight on the performance of two well known operational Ridge Regression estimators by deriving the moments of their stochastic shrinkage parameters. We also show that, under certain conditions, one of them has bounded moments.     

A Validation of the Subjective Vitality Scale Using Structural Equation Modeling

Ryan and Fredericks (1997) measure of vitality, thesubjective feeling of being alive and alert, wasdeveloped in the context of a single factor analysis.The present investigation employed structural equationmodeling (SEM) to assess construct validity andutility of the new measure. A large sample (N = 526) wascollected in two waves, allowing the investigators tofurther develop the model proposed by Ryan andFrederick, and to then validate it on a second dataset. The final model is presented, and the process ofachieving that model is discussed, as are the relativestrengths of SEM in test development.     

Some Asymptotic Properties of Ridge Regression in a System of Seemingly Unrelated Regression Equations

A discussion is made of asymptotic properties of an Operational Ordinary Ridge Regression estimator and comparison is made with the Operational Generalized Least Squares estimator. Also, some simulation experiments are carried showing efficiency gains can be made through the use of de Ridge estimator.     

Preserving the unpreservable: docile and unruly objects at MoMA

The aim of this article is to theorize how materials can play an active, constitutive, and causally effective role in the production and sustenance of cultural forms and meanings. It does so through an empirical exploration of the Museum of Modern Art of New York (MoMA). The article describes the museum as an “objectification machine” that endeavors to transform and to stabilize artworks as meaningful “objects” that can be exhibited, classified, and circulated. The article explains how the extent to which the museum succeeds in this process of stabilization ultimately depends on the material properties of artworks and, more specially, on whether these behave as “docile” or “unruly” objects. Drawing on different empirical examples, the article explores how docile and unruly objects shape organizational dynamics within the museum and, through them, the wider processes of institutional and cultural reproduction. The article uses this empirical example to highlight the importance of developing a new “material sensibility” that restores heuristic dignity to the material within cultural sociology.