TESTING SPHERICITY UNDER A MIXTURE MODEL

The robustness of Mauchly's sphericity test criterion when sampling from a mixture of two multivariate normal distributions is studied. The distribution of the sphericity test criterion when the sample covariance matrix has a non-central Wishart density of rank one is derived in terms of Meijer's G-functions; its distribution under the mixture model is then deduced. The robustness is studied by computing actual significance levels of the test under the mixture model using the critical values under the usual normal model.     

Will taxpayers ever like taxes?: Responses to the U.S. Tax Reform Act of 1986

Major policy changes like the 1986 Tax Reform Act (TRA) in the United States provide natural experiments to study attitudinal and behavior responses to law. Surprisingly, public evaluations of the TRA became increasingly negative after passage, while general support for the tax system became more positive in response to the changes. To explain this puzzle, we propose a dynamic model of taxpayer attitudes that is consistent with the observed loose linkage between logically-connected concepts. We briefly review the political context, objectives and impacts of the 1986 Tax Reform Act, and present several studies testing the impact of self-interest, prior beliefs, and social discussion on changes in attitudes and behavior.Results suggest that the complexity of taxes and difficulty in knowing objective impacts weakens the role of self-interest in attitudinal changes, thereby strengthening the role of prior beliefs and discussion. Evaluations of tax laws are most responsive to more politically-oriented influences.     

Children's gender- and age-based categorization in similarity and induction tasks

The present studies examined children's and adults' preferences for gender- or age-based categorization using similarity and inductive inference tasks. Four-year-olds, 6-year-olds, and adults looked at pictures of people and decided which of two was more like a target (similarity condition) or which shared a novel age- or gender-related property with the target (inference condition). Age or gender-based matches were possible. The results are consistent with previous findings that gender-based classification decreases with age. However, they also demonstrate that children use gender more for judging similarity than for making inferences about novel properties. Distinct patterns emerge from the two tasks: 6-year-olds and adults in both conditions categorize more by age than gender; 4-year-olds categorize by gender more than age in the similarity task, but by age more in the induction task. Only adults differentiated by property in the inference condition. These findings suggest that the salience of gender categories cannot entirely be attributed to their inductive potential. Gender has a salience beyond what would be predicted by its power for directing novel generalizations.     

MINING ERROR VARIANCE AND HITTING PAY-DIRT:

According to traditional error theory, sentiment measurements vary unsystematically from individual to individual. However, we find some patterned deviation in sentiments that characterize subsets of respondents within a seemingly homogeneous population. After demonstrating the existence of such patterns, we report an exploratory study aimed at identifying social characteristics of people with different patterns of sentiments. People embedded in multiple social networks have exaggerated sentiments that contour cultural patterns, and people with few social associations have attenuated sentiments conveying cultural detachment. In addition, people with disciplinary parents and romantic privation have some distinctive sentiments, depending on their gender.     

Coping with work stress: Psychological benefits of exercise

Although the health-enhancing effects of physical exercise have been well documented, less is known about how exercise benefits stressed employees psychologically. This article examines exercise as a coping response, and identifies changes in self-schemata (a person's underlying belief systems about him or herself) as the means by which exercise affects coping resources. In addition, by drawing on schema theory and the exercise literature, the active components of an exercise programme and the individuals who might enhance their ability to cope with stress through such a programme are identified.     

Estimation of noncentrality parameters

We propose some estimators of noncentrality parameters which improve upon usual unbiased estimators under quadratic loss. The distributions we consider are the noncentral chi-square and the noncentral F. However, we give more general results for the family of elliptically contoured distributions and propose a robust dominating estimator.     

Using the lessons learned from US and English law to create a regulatory framework for charities in evolving democracies

The evolving democracies of Eastern Europe and the former USSR republics are keenly interested in establishing charities. They have little law on this issue because their former governments did not encourage the development of charities. This article compares US and English regulation of charities and proposes a regulatory framework based on what the authors believe are the best attributes of both. Although the framework is based on the common law system, it can be adapted to the civil law systems of the Eastern European nations and the former USSR republics. The article includes such issues as developing a body of law, tax relief and creating a regulatory agency.Mr Hopkins is a lawyer with Powers, Pyles & Sutter, 1275 Pennsylvania Ave., N.W., Washington, D.C. 20007, and author ofThe Law of Tax-Exempt Organizations (1992a).Ms Moore is also a lawyer, 5908 N. 35th St., Arlington, Virginia 22207.The authors would like to thank Mssrs Kersi Shroff and Stephen F. Clarke, Senior Legal Specialists, American-British Law Division, Library of Congress, and Mr. William H. Morris, an attorney at Steptoe & Johnson, Washington, D.C., for their kind assistance during the researching of this article.     

Policy and practice for response to foster families when child abuse or neglect is reported.

For reasons discussed in this article, it is in the nature of family foster care that allegations of abuse and/or neglect in foster homes will arise. How an agency acts before, during, and after these eventualities has long-lasting implications for the well-being of foster children and of foster parents and their own children, as well as for foster home recruitment.