A competing risks derivation of a mixture model for the analysis of survival data

Boag (1949) and Berkson and Gage (1952) proposed a mixture model for the analysis of survival time data when aproportion of treated patients are cured. This paper presents a derivation of the Boag/Berkson-Gage mixture model as well as a eneralization of the model based on the theory of competing risks. The assumptions underlying the model are stated and discussed and a general likelihood function is obtained. Use of the model is illustrated ith data from the Stanford Heart Transplant Program.     

The Foster–Greer–Thorbecke (FGT) poverty measures: 25 years later

Twenty-five years ago, the FGT class of decomposable poverty measures was introduced in Foster, Greer, and Thorbecke (Econometrica 52:761–776, 1984). The present study provides a retrospective view of the FGT paper and the subsequent literature, as well as a brief discussion of future directions. We identify three categories of contributions: to measurement, to axiomatics, and to application. A representative subset of the literature generated by the FGT methodology is discussed and grouped according to this taxonomy. We show how the FGT paper has played a central role in several thriving literatures and has contributed to the design, implementation, and evaluation of prominent development programs; the breadth of its impact is evidenced by the many topics beyond poverty to which its methodology has been applied. We conclude with a selection of prospective research topics.     

Applying Cognitive Theory to Statistics Instruction

This article presents five principles of learning, derived from cognitive theory and supported by empirical results in cognitive psychology. To bridge the gap between theory and practice, each of these principles is transformed into a practical guideline and exemplified in a real teaching context. It is argued that this approach of putting cognitive theory into practice can offer several benefits to statistics education: A means for explaining and understanding why reform efforts work; a set of guidelines that can help instructors make well-informed design decisions when implementing these reforms; and a framework for generating new and effective instructional innovations.     

An analysis of conservation attitudes and awareness around Kaziranga National Park,Assam, India: implications for conservation and development

Kaziranga National Park and World Heritage Site, Assam, India, situated in a region with a large and diverse human population, was recently expanded due to its global importance for the conservation of many endangered species. Here, we develop detailed demographic and socio-economic profiles of residents around Kaziranga to study conservation attitudes and awareness using a semi-structured survey of 590 households in 37 villages. Results show high variation in attitudes and awareness as a function of ethno-religious group, educational level, and socio-economic and immigration status, indicating more and different needs for economic interventions within some communities than others. We found a high degree of conservation awareness, but most people expressed negative conservation attitudes and almost all lost crops to wildlife. We highlight the complexity of conflict in the area and present a basis for electing a microsite planning approach for conservation and development in areas characterized by high ethnic diversity, high human population densities, and land-dependent large mammals that pose economic risks. The findings imply that highly localized development schemes and participatory approaches to resource management at the village level, coupled with greater efforts at education, are especially needed to achieve conservation and development goals in such cases.     

Science as a Strategy for Social Work

For more than one hundred years, various forms of science have been promoted to boost social work’s status as a profession. Evidence-based practice and talk about the science of social work are only the most recent manifestations of this pattern. Counter to this trend, this article argues that the latest upsurge of interest in scientific social work is no more likely than any of its predecessors to address the problems of the profession. Beginning with a linguistic analysis of the words science and scientific as positive signifiers, the article traces social work’s long history of science talk as a means of reassuring funding agencies and bolstering the profession’s status. Drawing on a critique of this discourse as the latest example of abstracted empiricism, it then contends that while scientific social work can only rarely capture what occurs in the field, its attempt to do so actually undercuts practitioners’ professional judgment and discretion. Last, after rejecting science talk as counterproductive, the article concludes with recommendations for an alternative strategy that might better position social work to reconcile its advocacy of social justice with its concerns about its professional status.     

Land ownership,the subsistence constraint,and the demographic transition

We develop a novel model of fertility choice predicting an increase and subsequent decrease in fertility levels without introducing a quality–quantity tradeoff, mortality changes, or urbanization. The model highlights the roles of a subsistence constraint and non-wage income deriving from the ownership of land. We show that the sign of the effect of the wage rate on fertility depends on whether non-wage income is greater or less than a minimum consumption level. Suggestive evidence supporting the model, on changes in fertility from 1851 to 1891 across French départements, is provided. Finally, we embed our static model in a model of endogenous growth, and provide a numerical illustration of the working of the model.     

Committee Decision Making in Organizations: An Experimental Test of the Core

One concept that has been widely supported in experiments on predicting the outcome of majority-rule voting committees is the Core, the set of alternatives that cannot be defeated by any other in a binary contest. Unfortunately, the applicability of these experiments to organizations is limited by a set of rigid controls intended to ensure that the experiments are internally valid. This paper tests the Core in a laboratory environment that relaxes these controls. The Core is found to be highly predictive under these relaxed conditions, thereby enhancing confidence in its external validity.     

Urban predator–prey association: coyote and deer distributions in the Chicago metropolitan area

We examined how predator or prey presence, as well as local and landscape factors, influence the distribution of coyotes (Canis latrans) and white-tailed deer (Odocoileus virginianus) in the Chicago metropolitan area. We collected data for 2 years at 93 study sites along 3 transects of urbanization using motion-triggered cameras. Our primary objective was to determine the relationship among coyote and deer spatial and temporal distribution, habitat characteristics, and human activity using multi-season patch occupancy models. Coyote occupancy was most strongly linked to rates of site visitation by humans and dogs, and was more likely farther from the urban center, with coyote colonization of sites inversely related to road density, housing density, and human and dog site visitation. Deer more frequently occupied sites with high canopy cover near water sources and colonized smaller sites with reduced housing density and human and dog presence. Expected predator–prey dynamics were altered in this highly urban system. Though we predicted deer would avoid coyotes on the landscape based on an “ecology of fear” framework, deer and coyote occupancy showed a strong positive association. We suggest that a scarcity of quality habitat in urban areas may cause the species to co-occupy habitat despite potential fawn predation. Modifying human foot traffic in green spaces may represent a useful tool for management and conservation of large urban mammals.