Empirical transform estimation for indexed stochastic models

We present a method for estimating the parameters in indexed stochastic models via a least squares approach based on empirical transforms. Asymptotic approximations are derived for the distribution of the resulting estimators. An explicit expression for the mean-squared error provides a natural way of selecting the transform variable, and a numerical example illustrates the performance of the resulting method. A common finding, which we term 'diagonal optimization', occurs when multiparameter models are fitted by using transforms. Diagonal optimization arises when optimal performance results from equating the elements of the transform vector, and we provide a heuristic explanation of why this occurs.     

DENSITY FUNCTION APPROXIMATION WITH PARTICULAR REFERENCE TO THE DISTRIBUTION OF OVERLAP OF CIRCLES

Given that two circles overlap, the area in common is a function of the distance between their centres. This paper adopts a suitable random distribution for the intercentre distance and then derives the distribution of the area of overlap. An approximation is sought for the density function using a criterion which enables bounds to be placed on the difference between the moments of the density function and those of the approximation. This is an approach of general applicability. The importance of matching the end-point behaviour of the density and the approximation is stressed. It is shown that the distribution of the area of overlap may be well approximated by a mixture of beta distributions in which the parameters change smoothly with the ratio of radii.     

Cost-effectiveness of family-based substance abuse treatment

In order to compete in a financially sensitive health care system, family systems-based treatments must demonstrate effective clinical results as well as cost-effectiveness. Cost-effectiveness research can demonstrate to health care insurers and policy makers which treatments are viable options for implementation. The present literature review identified eight cost-effectiveness family-based substance abuse treatment studies. The results suggest that certain family-based treatments are cost-effective and warrant consideration for inclusion in health care delivery systems.     

Designing Risk Communications: Completing and Correcting Mental Models of Hazardous Processes, Part I

Many risk communications are intended to help the lay public make complex decisions about risk. To guide risk communicators with this objective, a mental models approach to the design and characterization of risk communications is proposed. Building on text comprehension and mental models research, this approach offers an integrated set of methods to help the risk communication designer choose and analyze risk communication content, structure, and organization. An applied example shows that two radon brochures designed with this approach present roughly the same expert facts as a radon brochure widely distributed by the U.S. EPA but meet higher standards on other content, structure, and organization criteria.     

The Educational Consequences of Teen Childbearing

A huge literature shows that teen mothers face a variety of detriments across the life course, including truncated educational attainment. To what extent is this association causal? The estimated effects of teen motherhood on schooling vary widely, ranging from no discernible difference to 2.6 fewer years among teen mothers. The magnitude of educational consequences is therefore uncertain, despite voluminous policy and prevention efforts that rest on the assumption of a negative and presumably causal effect. This study adjudicates between two potential sources of inconsistency in the literature—methodological differences or cohort differences—by using a single, high-quality data source: namely, The National Longitudinal Study of Adolescent Health. We replicate analyses across four different statistical strategies: ordinary least squares regression; propensity score matching; and parametric and semiparametric maximum likelihood estimation. Results demonstrate educational consequences of teen childbearing, with estimated effects between 0.7 and 1.9 fewer years of schooling among teen mothers. We select our preferred estimate (0.7), derived from semiparametric maximum likelihood estimation, on the basis of weighing the strengths and limitations of each approach. Based on the range of estimated effects observed in our study, we speculate that variable statistical methods are the likely source of inconsistency in the past. We conclude by discussing implications for future research and policy, and recommend that future studies employ a similar multimethod approach to evaluate findings.     

Social class and workers’ rent, 1983–2001

Sociologists and economists continue to seek explanations for the growth of earnings inequality since the late 1970s. In this article, we draw upon the structural tradition of labor market analysis in sociology in order evaluate the conjecture that selective rent destruction is a source of the recent increase in earnings inequality. In empirical analysis of the Outgoing Rotation Groups of the Current Population Surveys from 1983 to 2001, we demonstrate that (1) the earnings of workers at the bottom of the class distribution have declined relative to the earnings of those at the top and (2) the variance of wage premia associated with employment in alternative industries has declined relatively more for those at the bottom of the class distribution. Adopting the position from both the sociology and labor economics literatures that these industry wage premia are reasonable measures of industry rents, we conclude that the results support the rent destruction conjecture and, by implication, that structural models of labor markets can explain some of the increase in earnings inequality.     

A social ecology approach and applications of urban ecosystem and landscape analyses: a case study of Baltimore,Maryland

The early interactions between plant, animal, and human ecology in the 1920s in the United States provide an initial basis for understanding and directing an integrated ecosystem approach to the study of sociocultural and biophysical patterns and processes of present day cities. However, whereas the human ecology approach of the 1920s and 30s was interested in metaphorical similarities with plant and animal ecologists, we propose a more integrated approach to human ecosystem observation and analysis. A critical feature to an integrated, urban ecosystem approach is the ability of researchers to address the spatial heterogeneity of urban ecosystems; i.e. the development and dynamics of spatial heterogeneity and the influences of spatial patterns on cycles and fluxes of critical resources (e.g. energy, materials, nutrients, genetic and nongenetic information, population, labor, and capital). An important question in this context is how differential access to and control over critical resources affect the structure and function of urban ecosystems.To address this heterogeneity, we illustrate a human ecosystem and landscape approach and how the concept of social differentiation can be applied spatially at different scales with a case study from our research in Baltimore, Maryland. Further, we identify different methods, tools, and techniques that can be used for an integrated, urban ecosystem approach.     

Generational equity and measurement bias: Who is really poor?

One core contention of the generational equity argument is that elderly people are financially well-off. To support this argument, generational equity proponents compare poverty rates of elderly people to those of children in the United States demonstrating that elderly people enjoy a privileged position in terms of financial well-being as compared to other age groups. I argue that the measurement of poverty upon which this argument is based is grounded in faulty logic and incorrect assumptions. Therefore, the basis of this generational equity argument is invalid. I conclude that using poverty rates creates the impression of a conflict between children and elderly people drawing attention away from the continuing problem of discrimination against women and minorities.