Redundancy in Designs

The author contends that a previous Risk Analysis article overemphasized the pitfalls of incorporating redundancy into designs. Relevant aspects of that article are reviewed and commented upon, then the potentials and pitfalls of redundancy in systems and procedures are more broadly discussed. To provide a solid foundation for that discussion, some definitions for systems risk analysis terminology are presented. It is shown that pairs and larger sets of related failures (the physical causes of shortfalls in redundancy effectiveness) can be divided into two types: (1) cascading/induced failures and (2) common-external-cause failures. Each type has its own physical characteristics and implications for mathematical modeling. Service experience with large-commercial-airplane jet-engine propulsion systems is used to illustrate the two types of related failures. Finally, an overview is provided of event-sequence analysis, an alternative approach to systems risk analysis. When the possibility of related failures of mutually-redundant system elements must be accounted for, event-sequence analysis can usually do that better than fault-tree analysis.     

African American Stepfather–Stepchild Relationships,Marital Quality,and Mental Health

ABSTRACT

This study examined associations between stepfather–stepchild relationship quality, stepfathers’ depressive symptoms, and two aspects of marriage: marital quality and positive marital interactions. Marital quality was assessed in terms of commitment, trust, passionate and friendship-based love, and happiness. Marital interactions were assessed in terms of intimacy, shared activities, and verbal communication. Using data collected from 149 recently married African American stepfathers, structural equation modeling revealed that when stepfathers reported more positive relationships with their stepchildren, they also reported more positive marital quality and a higher frequency of positive marital interactions (relationship-solidifying activities), and that, in turn, was associated with stepfathers experiencing fewer depressive symptoms.     

Learning Style Preferences of Undergraduate Social Work Students

It has been identified that undergraduate social work students have distinctive learning needs. The purpose of this study was to investigate the learning style preferences of a group of undergraduate social work students enrolled at a large Australian university. The Kolb Learning Style Inventory, Index of Learning Styles and Success Types Learning Style Type Indicator was distributed to 606 students enrolled in an undergraduate social work degree at one metropolitan Australian university. A total of 116 questionnaires were returned, providing a response rate of 19.14%. The results indicated that converging and assimilating, intuitive and sensing, thinking, judging and perceiving learning styles were favoured by this group of social work students. It is recommended that educators understand and take into consideration the learning style preferences of undergraduate social work students when developing curricula and evaluating teaching approaches, especially when planning and implementing education initiatives. This will help create effective learning environments, appropriate learning opportunities and a contemporary curriculum for social work students.     

The case for (promoting) marriage: The devil is in the details

This article considers the quality of the evidence that marriage confers unique benefits, and that, as such, social policies should be enacted to encourage couples, particularly those with few economic resources, to get married and stay together. Public concern about the future of marriage in the United States, we show, is rooted in demographic changes that reflect not so much a turning away from marriage, but an increasing openness to postponing marriage, living together out of wedlock, or divorcing. We examine why people who are motivated to marry hold back from doing so when they see the warning signs of future problems, and what happens when they marry despite them. We argue that marriages are fashioned in the images of the partners and are shaped by the opportunities and constraints of the ecological settings in which they are situated. As such, the promotion of family health and stability will require an approach that attends to couples' psychological, social, and economic needs.     

Testing for Slope Heterogeneity Bias in Panel Data Models

ABSTRACT

Standard econometric methods can overlook individual heterogeneity in empirical work, generating inconsistent parameter estimates in panel data models. We propose the use of methods that allow researchers to easily identify, quantify, and address estimation issues arising from individual slope heterogeneity. We first characterize the bias in the standard fixed effects estimator when the true econometric model allows for heterogeneous slope coefficients. We then introduce a new test to check whether the fixed effects estimation is subject to heterogeneity bias. The procedure tests the population moment conditions required for fixed effects to consistently estimate the relevant parameters in the model. We establish the limiting distribution of the test and show that it is very simple to implement in practice. Examining firm investment models to showcase our approach, we show that heterogeneity bias-robust methods identify cash flow as a more important driver of investment than previously reported. Our study demonstrates analytically, via simulations, and empirically the importance of carefully accounting for individual specific slope heterogeneity in drawing conclusions about economic behavior.     

Comparison of Amish and Non-Amish Farmers: A Diffusion/Farm-Structure Perspective1

Abstract Considerable attention has focused on farming practices and behavioral patterns that characterize Amish farmers from other agriculturalists. It has been suggested that Amish farmers are more concerned about the physical environment than non-Amish farmers because Amish employ fewer technology-intensive farming practices, though there is little empirical evidence to support such an assertion. To address this issue, data were collected from a sample of Amish and non-Amish owner-operators in Ohio to compare environmental attitudes and farming systems presently in use. Discriminant analysis was used to examine factors chosen to differentiate the two groups. Findings reveal that Amish respondents believed more strongly than other farmers that ground water pollution was an important environmental problem and that farmers should reduce chemical application rates to protect ground water resources. Other farmers exhibited greater willingness to participate in educational programs designed to reduce pesticide application rates. The two groups could not be differentiated by criteria used to make adoption decisions about farm technologies and farming practices; both used productivity and efficiency criteria when making adoption decisions.     

From tragedy to triumph: a segue to community building for children and families

In 2000, more than 60 nonprofit agencies, health care providers, government officials, and community advocates in Tarrant County, Texas, came together to work for systemic change in the mental health care system. The coalition, known as the Mental Health Connection, began working toward a "No Wrong Door" approach to mental health services, which required aggressive coordination between federal, private, and nonprofit resources. The result is a five- to six-year plan for implementation of a new systems of care model for children with severe emotional disturbances and their families. The Mental Health Connection also focuses on legislative advocacy to bring about necessary policy changes at the local, state, and federal levels. Finally, the coalition focuses on developing sustainable revenue streams that will allow the new systems to remain in place once the group accomplishes the initial mission of the Mental Health Connection.     

Hidden in Plain Sight: Maroon Life and Labor in Virginia's Dismal Swamp

Nineteenth-century maroons in Virginia's Great Dismal Swamp formed communities within communities, whose members were set apart from others not so much by space (an impenetrable wilderness) but by the legal status they renounced, the fugitive status they embraced, and the common goal of creating meaningful lives neither fully within, nor completely apart from, surrounding slave society. The following analysis of one group of Great Dismal Swamp maroons offers scholars a new way to conceptualize marronage in nineteenth-century North America. Rather than look only to remote places for traces of maroon societies, researchers might also consider examining such communities in more settled areas, including centers of large-scale industrial operations, where fugitives carved out identities and negotiated their wages within a biracial labor system that relied upon and supported slavery.