Heteroscedastic Global Tests that the Regression Parameters for Two or More Independent Groups are Identical

Simulation results are reported on methods that allow both within group and between group heteroscedasticity when testing the hypothesis that independent groups have identical regression parameters. The methods are based on a combination of extant techniques, but their finite-sample properties have not been studied. Included are results on the impact of removing all leverage points or just bad leverage points. The method used to identify leverage points can be important and can improve control over the Type I error probability. Results are illustrated using data from the Well Elderly II study.     

Linguists and other animals

Book reviewed in this article:
Joan Dunayer, Animal Equality: Language and Liberation     

How Welfare Policies Affect Adolescents' School Outcomes: A Synthesis of Evidence From Experimental Studies

Using data from 8 random assignment studies and employing meta‐analytic techniques, this article provides systematic evidence that welfare and work policies targeted at low‐income parents have small adverse effects on some school outcomes among adolescents ages 12 to 18 years at follow‐up. These adverse effects were observed mostly for school performance outcomes and occurred in programs that required mothers to work or participate in employment‐related activities and those that encouraged mothers to work voluntarily. The most pronounced negative effects on school outcomes occurred for the group of adolescents who had a younger sibling, possibly because of the increased home and sibling care responsibilities they assumed as their mothers increased their employment.     

Fundamentals of Theory and Practice Revisited; The Mutiny and the Bounty: The Place of Milan Ideas Today

The author traces the development of the Milan approach from the beginning, through the split into two teams in 1980, and subsequent developments in theory and application. He identifies possible unrecognised or undeclared influences of Milan in other family therapy approaches.     

Scheduling Updates of Probabilistic Risk Assessments: The Arkansas Nuclear One-Unit 1 Experience

This paper presents the results of a study that identified how often a probabilistic risk assessment (PRA)should be updated to accommodate the changes that take place at nuclear power plants. Based on a 7-year analysis of design and procedural changes at one plant, we consider 5 years to be the maximum interval for updating PRAs. This conclusion is preliminary because it is based on the review of changes that occurred at a single plant, and it addresses only PRAs that involve a Level 1 analysis (i.e., a PRA including calculation of core damage frequency only). Nevertheless, this conclusion indicates that maintaining a useful PRA requires periodic updating efforts. However, the need for this periodic update stems only partly from the number of changes that can be expected to take place at nuclear power plants–changes that individually have only a moderate to minor impact on the PRA, but whose combined impact is substantial and necessitates a PRA update. Additionally, a comparison of two generations of PRAs performed about 5 years apart indicates that PRAs must be periodically updated to reflect the evolution of PRA methods. The most desirable updating interval depends on these two technical considerations as well as the cost of updating the PRA. (Cost considerations, however, were beyond the scope of this study.)     

Naivety and Family Therapy An Interview with John Carpenter

Family therapists have been naive about families, the pressures on them and the contexts of therapy. Therapists should be clear about their roles, sensitive to families' experience of therapy, and resist the temptation to mystify therapy. John Carpenter is Senior Lecturer in Mental Health, University of Kent, Canterbury, England and Co-Editor of Journal of Family Therapy. He was a guest keynote speaker at the 1991 Australian Family Therapy Conference in Brisbane, and this interview took place shortly afterwards in Melbourne.     

The Market Provision of Management Services, Information Asymmetries and Service Quality—Some Market Solutions: an Empirical Example

This article examines the problems of information asymmetry associated with the market provision of managerial services. Such problems are heightened by those characteristics which differentiate services from goods. Two unique, and central, characteristics of services, are intangibility and perishability. These create special problems for the market provision of services. In particular they make for difficulties in assessing quality; whereas the producer may know product quality, the buyer often does not. The asymmetry between sellers and buyers is of two types: Adverse selection and moral hazard. Adverse selection occurs when the buyer cannot observe the relevant characteristics of the seller or the conditions under which they work. The problem of moral hazard is the buyer's inability to observe the action taken by the sellers. If these difficulties are not overcome, the market could collapse as companies withdraw and internalize service provision. However, each market has a number of in-built mechanisms which remedy the harmful effects associated with information-related problems. The institutional arrangements which predominate in particular markets are dependent upon the trust-producing mechanisms within those markets. Consequently, market responses to information asymmetries are far from uniform. The argument is illustrated using the example of the executive recruitment industry. In this respect the paper is a highly focused study of those mechanisms which overcome information asymmetries in one service market.     

Racial differences in urban neighboring

Despite mixed expectations generated by existing theories and evidence, this analysis documents clear racial differences in urban neighboring behavior. Using data from a survey of Nashville, Tennessee, residents, we show that blacks interact with their neighbors more often than whites do, and in a greater variety of ways. The only noteworthy similarity between the two groups is the positive impact of neighboring on feelings of community affect. Overall, our results support the view that neighbor relations — like other kinds of informal participation — have helped blacks cope with constrained social opportunities and provided them with access to resources unavailable through formal institutional channels.Revised version of a paper presented at the annual meeting of the American Sociological Association, San Francisco, August 1989.