Consideration of Background Exposures in the Management of Hazardous Waste Sites: A New Approach to Risk Assessment

The current approach to health risk assessment of toxic waste sites in the U.S. may lead to considerable expenditure of resources without any meaningful reduction in population exposure. Risk assessment methods used generally ignore background exposures and consider only incremental risk estimates for maximally exposed individuals. Such risk estimates do not address true public health risks to which background exposures also contribute. The purpose of this paper is to recommend a new approach to risk assessment and risk management concerning toxic waste sites. Under this new approach, which we have called public health risk assessment, chemical substances would be classified into a level of concern based on the potential health risks associated with typical national and regional background exposures. Site assessment would then be based on the level of concern for the particular pollutants involved and the potential contribution of site contaminants to typical background human exposures. While various problems can be foreseen with this approach, the key advantage is that resources would be allocated to reduce the most important sources of human exposure, and site remediation decisions could be simplified by focussing on exposure assessment rather than questionable risk extrapolations.     

The location of ethnic and racial groups in the United States

The distinctive regional and urban locational patterns of thirty-three ethnic groups in the United States are analyzed from two different perspectives. First, who are the numerically important groups in each region? Second, from the perspective of the groups themselves, where are they spatially concentrated? We hypothesize that the forces generating distinctive ethnic locational patterns are strongest at the time of the initial settlement; thus the longer a group has been present in the United States, the less geographically concentrated it will be. This is found to be true for most ethnic groups except blacks and American Indians, whose specific social and political situations explain their particular concentrations. However, the early settlement patterns still affect the ethnic makeup of various areas of the nation, even though the concentrations have diminished over time. Moreover, although the 1975–1980 patterns of internal migration (analyzed through a Markov Chain model) are tending to reduce some of the distinctive geographic concentrations in the nation, this will still not fully eliminate distinctive ethnic concentrations. Groups differ in their propensities to leave or enter each area in a way that reflects the existing ethnic compositions of the areas. Thus even with the massive level of internal migration in the nation, there is no evidence that the substantial ethnic linkage to region is disappearing.     

The Entrepreneurial Tendencies of Managers: a Research Note

In this study associations are sought between certain biographical, family, personality and career variables and the likelihood that managers will develop their own business venture. Results, based on an analysis of questionnaires completed by 194 managers, reveal that ownership of a business by self or parents together with certain personal characteristics predispose managers towards business founding. Contrary to expectations, job and career frustration does not incline managers towards proprietorship.     

Demography of disaster: Population estimates after hurricane Andrew

Hurricane Andrew blasted through the southern tip of Florida in August 1992, damaging or destroying tens of thousands of homes and forcing hundreds of thousands of persons to move at least temporarily to different places of residence. The hurricane not only disrupted the lives of many Floridians, but destroyed the statistical basis for producing local population estimates in South Florida as well. These estimates are used for many types of decision-making, from the distribution of state revenue-sharing dollars to choosing sites for fast-food restaurants. This article describes the estimation problems created by the hurricane and how those problems were resolved through the use of existing data sources and the collection of new types of data. It closes with a discussion of several conceptual, methodological and procedural issues that will have to be faced in virtually any attempt to estimate the demographic consequences of natural disasters.An earlier version of this paper was presented at the 1994 annual meeting of the Population Association of America, Miami, Florida, USA.     

Tree-structured subgroup analysis for censored survival data: Validation of computationally inexpensive model selection criteria

The performance of computationally inexpensive model selection criteria in the context of tree-structured subgroup analysis is investigated. It is shown through simulation that no single model selection criterion exhibits a uniformly superior performance over a wide range of scenarios. Therefore, a two-stage approach for model selection is proposed and shown to perform satisfactorily. Applied example of subgroup analysis is presented. Problems associated with tree-structured subgroup analysis are discussed and practical solutions are suggested.     

Projection and Misperception in Couples Treatment

Projective identification is discussed as an interpersonal mechanism involved in distortions of perceptions and communications. Several case illustrations are presented to show how this mechanism manifests itself in relatively healthy, though neurotic, couples. A treatment approach based on correction of the perceptual distortions is suggested as a model for short-term counseling with such couples.     

Dempster's combination rule and sufficient statistics

In his articles (1966-1968) concerning statistical inference based on lower and upper probabilities, Dempster refers to the connection between Fisher's fiducial argument and his own ideas of statistical inference. Dempster's main concern however focuses on the “Bayesian” aspects of his theory and not on an elaboration of the relation between Fisher's and his ideas. This article attempts to work out the connection between those two approaches and focuses primarily on the question, whether Dempster's combination rule, his upper and lower probabilty based on sufficient statistics and inference based on sufficient statistics in Fisher's sense are consistent. To be adequate to Fisher's reasoning, we deal with absolutely continuous, one parametric families of distributions.This is certainly not the usual assumption in context with Dempster's theory and implies a normative but straightforward definition concerning the underlying conditional distribution; this definition however is done in Dempster's spirit as can be seen from his articles, (1966, 1968,a,b). Under those assumptions it can be shown that - similar to Lindley's results concerning consistency in fiducial reasoning (1958) - the combination rule, Dempster's procedure based on sufficient statistics and fiducial inference by sufficient statistics agree iff the parametric family under consideration can be transformed to location parameter form.     

Parenting and child-caretaking among black men who have sex with men and associated sexual and reproductive health factors: a brief report

Abstract

The purpose of this exploratory study was to examine the prevalence of parenting and child-caretaking among a sample of black men who have sex with men (MSM), as well as associations between parenting roles and sexual and reproductive health (SRH) factors. Parenting and SRH data were derived from a survey of 199 black MSM. Nearly half of the sample reported being a father or father-figure (44.4%), almost a third indicated serving as caretaker of a child (29.1%), and one in five have a biological child (20.1%). Over half of the sample reported at least one of these three parenting/child-caretaking roles (52.5%). Two significant differences were observed for sexual health variables: men with biological children were significantly more likely to report using condoms inconsistently (55.0% vs. 35.7%, p = .026) and engaging in transactional sex work (36.8% vs. 21.0%, p = .041). Given the observed prevalence, parenting and child-caretaking among black MSM warrant further inquiry as factors that may influence SRH outcomes and care utilization. Services and interventions tailored to black MSM should consider these men’s potential roles and responsibilities as parents and caretakers of children.     

Value drivers of social businesses: A business model perspective

Hybrid organizational forms that combine commercial and welfare institutional logics play an increasingly important role in addressing the grand societal challenges we face today. Building on the literatures on hybrid organizations and social business models, we explore the characteristics of social businesses from a business model perspective. This study seeks to better understand the particularities and value drivers of hybrid social purpose in contrast to purely commercial business models. We follow a grounded theory approach and our findings are based on interview data from 17 social business firms. Building on social businesses' identified particularities, we propose four value drivers of social business models: 1) responsible efficiency, 2) impact complementarities, 3) shared values, and 4) integration novelties. We link our findings to the literature, contributing new insights into social businesses models and implications for practitioners.