Combinatorial Equivalence of Fractional Factorial Designs

Two symmetrical fractional factorial designs are said to be combinatorially equivalent if one design can be obtained from another by reordering the runs, relabeling the factors and relabeling the levels of one or more factors. This article presents concepts of ordered distance frequency matrix, distance frequency vector, and reduced distance frequency vector for a design. Necessary conditions for two designs to be combinatorial equivalent based on these concepts are presented. A new algorithm based on the results obtained is proposed to check combinatorial non-equivalence of two factorial designs and several illustrating examples are provided.     

Adoption and Termination of Employee Involvement Programs

Using an interview survey of manufacturing establishments that provide 10 years of retrospective data on labor practices, we investigate factors associated with the adoption and termination of employee involvement programs and the relation between these and other human resource policies. In the period studied, more firms introduced than terminated such programs but a sufficiently large number chose to eliminate such programs to indicate that employee involvement does not fit in all business settings. Our results show that business strategy and the use of other complementary human resource policies affect the dynamics of employee involvement use in US manufacturing establishments.     

Corporate political power and US foreign policy, 1981–2002: the role of the policy-planning network

Theory and Society - Recent empirical work has offered strong support for ‘biased pluralism’ and ‘economic elite’ accounts of political power in the United States, according...     

Sustainable landscaping programs in the United States and their potential to encourage conservation and support ecosystem services

Sustainable landscaping programs are voluntary initiatives that recommend a set of practices to improve the environmental quality of urban ecosystems by providing landscaping materials, guidelines, and educational resources. Our goal was to examine the recommendations and outcomes of these programs in the United States and their value for encouraging conservation practices in residential ecosystems. We conducted a comprehensive web search and identified 193 sustainable landscaping programs in the United States. Programs aim to increase native species richness, affordably manage stormwater runoff, and offer residents meaningful experiences with nature. Sustainable landscaping programs present many opportunities to engage people with local ecological knowledge and conservation practices, provide accessible spaces for environmental education, cultivate interdisciplinary research collaborations, and advance inclusion in conservation. However, assessments of their ecological value are rare, leaving many questions surrounding the benefits to biodiversity and water quality afforded by participation. Many programs also require investments in landscaping materials and certification fees that might limit participation by some households. Future work should examine how recommended practices influence urban biodiversity, identify and address barriers to participation, and generate social-ecological knowledge that can inform future programs.

     

Climate events and the role of adaptive capacity for (im-)mobility

Population and Environment - The study examines the relationship between sudden- and gradual-onset climate events and migration, hypothesizing that this relationship is mediated by the adaptive...     

Subjective Health-Related Quality of Life in Homeless and Vulnerably Housed Individuals and Its Relationship with Self-Reported Physical and Mental Health Status

Although the association between homelessness and objective indicators of poor health is well-established, little research has focused on the subjective health-related quality of life of homeless and vulnerably housed (HVH) individuals. This study examined the subjective health-related quality of life of HVH individuals, using the Multiple Discrepancies Theory (MDT) Scale for Health of the Quality of Life for Homeless and Hard-to-House Individuals (QoLHHI) Inventory, and its association with self-reported functional health status, as measured by the SF-12, and self-reported physical and mental health conditions in a sample of 100 HVH individuals recruited in Vancouver, Toronto and Ottawa. Our findings indicate that physical and mental health conditions are highly prevalent among HVH individuals and that the SF-12 Physical and Mental Component Summary scores are substantially lower compared to US population norms. The MDT Health items were not statistically significantly associated with physical or mental health conditions and only showed correlations of small to moderate magnitude with the SF-12 Component Summary Scales. These findings suggest that the QoLHHI MDT Scale for Health can provide information about HVH individuals’ subjective health experiences that is different from, and can serve as a valuable complement to, health status information for use in research and evaluation studies, as well as for policy purposes to make informed decisions based on subjective health-related quality of life data from HVH individuals.     

Adolescent Religiosity and School Contexts*

Objectives. Schools serve as the primary social organizations for adolescents, structuring their lives and conveying a variety of skills, norms, and values, but relatively little is known about how schools influence the development of religious belief, attitudes, and behavior during adolescence. We explore how schools' religious norms, coupled with adolescents' pursuit of social status through conformity, affect public and private religiosity. Methods. Employing data from the National Longitudinal Study of Adolescent Health (Add Health), we use multilevel modeling to examine the impact of school context on adolescents' public and private religiosity. Results. We find that school norms are influential in shaping both public religious expressions and private devotional activities, but pursuit of social status is a motivation for change across religious contexts only of public religious activity. The effect of social status as a motivator of religious change was moderated by the strength of the adolescent's identification with the school, especially for private religiosity. Conclusions. Schools play a key role in the social development of adolescents, and students' religious beliefs and behaviors are influenced systematically and observably by the type of religious climate within the school.     

Research on environmental health interventions: ethical problems and solutions

This article reviews a variety of ethical issues one must consider when conducting research on environmental health interventions on human subjects. The paper uses the Kennedy Krieger Institute lead abatement study as well as a hypothetical asthma study to discuss questions concerning benefits and risks, risk minimization, safety monitoring, the duty to warn, the duty to report, the use of control groups, informed consent, equitable subject selection, privacy, conflicts of interest, and community consultation. Research on environmental health interventions can make an important contribution to our understanding of human health and disease prevention, provided it is conducted in a manner that meets prevailing scientific, ethical, and legal standards for research on human subjects.     

The Legalization of Abortion and Subsequent Youth Homicide: A Time Series Analysis

In this article, we examine the association between the legalization of abortion with the 1973 Roe v. Wade decision and youth homicide in the 1980s and 1990s. An interrupted time series design was used to examine the deaths of all U.S. 15- to 24-year-olds that were classified as homicides according to the International Classification of Diseases (codes E960-969) from 1970 to 1998. The legalization of abortion is associated over a decade later with a gradual reduction in the homicides of White and non-White young men. The effect on the homicides of young women is minimal. We conclude that the 1990s decline in the homicide of young men is statistically associated with the legalization of abortion. Findings are not consistent with several alternative explanations, such as changes in the crack cocaine drug market. It is almost inconceivable that in the United States of today, policies affecting the choice to have children would be justified as a means to control crime. Yet, if the legalization of abortion had this unintended effect, the full range of policy implications needs to be discussed.     

Chemical Accidents in the United States, 1990–1996

Objective. Much of the empirical work on environmental justice centers on the geographic distribution of potential chronic health risks (e.g., planned toxic releases or treatment storage and disposal facilities). Far less attention has been devoted to the geographic distribution of acute health risks that cause immediate harm. The purpose of this work is to examine environmental justice in terms of potential acute health risks by examining the distribution of serious chemical accidents across diverse subpopulations. Methods. We draw upon 1990 census data for the United States to study the relationship between the racial, ethnic, and economic characteristics of census block groups ( N = 226,398) and the presence or absence of chemical accidents that caused at least one injury, death, or evacuation for the time period of 1990–1996. The data used to map the location of the chemical accidents were obtained from the Environmental Protection Agency's Accidental Release Information Program (ARIP) database. Results. Our results indicate that the acute risk associated with chemical accidents at fixed facilities is greater for individuals living in low–income census block groups, especially when comparisons are made within the counties where the chemical accidents occur. Our results concerning race and ethnicity are less consistent and somewhat weaker. Conclusions. Although these results do not show large and dramatic effects, as have often been found in the study of the social distribution of chronic environmental risk, they do stand as one of a relatively few social analyses of social variation in exposure to acute environmental risk.