The exponentiated Weibull distribution: a survey

A review is given of the exponentiated Weibull distribution, the first generalization of the two-parameter Weibull distribution to accommodate nonmonotone hazard rates. The properties reviewed include: moments, order statistics, characterizations, generalizations and related distributions, transformations, graphical estimation, maximum likelihood estimation, Bayes estimation, other estimation, discrimination, goodness of fit tests, regression models, applications, multivariate generalizations, and computer software. Some of the results given are new and hitherto unknown. It is hoped that this review could serve as an important reference and encourage developments of further generalizations of the two-parameter Weibull distribution.     

The beta generalized Rayleigh distribution with applications to lifetime data

For the first time, we propose a new distribution so-called the beta generalized Rayleigh distribution that contains as special sub-models some well-known distributions. Expansions for the cumulative distribution and density functions are derived. We obtain explicit expressions for the moments, moment generating function, mean deviations, Bonferroni and Lorenz curves and densities of the order statistics and their moments. We estimate the parameters by maximum likelihood and provide the observed information matrix. The usefulness of the new distribution is illustrated through two real data sets that show that it is quite flexible in analyzing positive data instead of the generalized Rayleigh and Rayleigh distributions.     

General results for the beta Weibull distribution

In this paper, we study some mathematical properties of the beta Weibull (BW) distribution, which is a quite flexible model in analysing positive data. It contains the Weibull, exponentiated exponential, exponentiated Weibull and beta exponential distributions as special sub-models. We demonstrate that the BW density can be expressed as a mixture of Weibull densities. We provide their moments and two closed-form expressions for their moment-generating function. We examine the asymptotic distributions of the extreme values. Explicit expressions are derived for the mean deviations, Bonferroni and Lorenz curves, reliability and two entropies. The density of the BW-order statistics is a mixture of Weibull densities and two closed-form expressions are derived for their moments. The estimation of the parameters is approached by two methods: moments and maximum likelihood. We compare the performances of the estimates obtained from both the methods by simulation. The expected information matrix is derived. For the first time, we introduce a log-BW regression model to analyse censored data. The usefulness of the BW distribution is illustrated in the analysis of three real data sets.     

Blocking in Healthcare Operations: A New Heuristic and an Application

We consider the problem of optimal capacity allocation in a hospital setting, where patients pass through a set of units, for example intensive care and acute care (AC), or AC and post‐acute care. If the second stage is full, a patient whose service at the first stage is complete is blocked and cannot leave the first stage. We develop a new heuristic for tandem systems to efficiently evaluate the effects of such blocking on system performance and we demonstrate that this heuristic performs well when compared with exact solutions and other approaches presented in the literature. In addition, we show how our tandem heuristic can be used as a building block to model more complex multi‐stage hospital systems with arbitrary patient routing, and we derive insights and actionable capacity strategies for a real hospital system where such blocking occurs between units.     

SOME OF THE UNDERLYING SELECTION CRITERIA FOR MIDDLE MANAGEMENT PERSONNEL IN FINANCIAL POSITIONS: A FACTOR ANALYTIC STUDY

A sample of middle managers were asked to make ratings regarding the importance of thirteen variables they considered when making decisions to select candidates into the ranks of middle management. These thirteen selection variables were developed based on previous research on managerial selection by Edwin Miller and on research conducted at General Electric by another investigator. The set of decision variables was then subjected to factor analysis in an effort to recover the fundamental structure of the decision space used to select middle managers. The analysis yielded encouraging results due to the distinctness with which certain factors were indicated. Three fundamental decision criteria were suggested: (1) a leadership-administrative skills factor, (2) a technical competence factor, and (3) a capability-willingness to work factor. These three factors were discussed in terms of their relevance to previous research on managerial selection.     

Questioning Consilience and Autonomy in Self-Determination Theory: A Critique and Hermeneutic-Phenomenological Alternative

This paper offers a theoretical analysis of Self-Determination Theory (SDT) and its claims regarding human autonomy. Self-determination theorists have advanced a form of self-regulated, engaged behavior (i.e., autonomy), founded upon on a consilient account of human motivation that assumes multiple, hierarchical levels of organization and causation (e.g., biological, psychological, and social). Autonomy, from this perspective, is taken to emerge from underlying biological mechanisms, but also able to exert its own causal effects in the world as a unique psychological phenomenon. We contend that in theorizing this way, self-determination theorists have invoked a mixed discourse of mechanism and autonomy that leaves important questions unanswered, perhaps most importantly those concerning how autonomy as a kind of volition can fit coherently in the mechanistic account of world that they advocate. We then offer an alternative perspective based upon the work of various hermeneutic-phenomenological thinkers in philosophy and psychology. This alternative perspective conceptualizes human phenomena such as autonomy and motivation in agentic terms, emphasizing meaningful participation in possibility-laden contexts of everyday practices.