Mixtures of modified t-factor analyzers for model-based clustering,classification, and discriminant analysis

A novel family of mixture models is introduced based on modified t-factor analyzers. Modified factor analyzers were recently introduced within the Gaussian context and our work presents a more flexible and robust alternative. We introduce a family of mixtures of modified t-factor analyzers that uses this generalized version of the factor analysis covariance structure. We apply this family within three paradigms: model-based clustering; model-based classification; and model-based discriminant analysis. In addition, we apply the recently published Gaussian analogue to this family under the model-based classification and discriminant analysis paradigms for the first time. Parameter estimation is carried out within the alternating expectation-conditional maximization framework and the Bayesian information criterion is used for model selection. Two real data sets are used to compare our approach to other popular model-based approaches; in these comparisons, the chosen mixtures of modified t-factor analyzers model performs favourably. We conclude with a summary and suggestions for future work.     

Doing Good,Public Good,and Public Value

In this article, using multiple illustrative case examples, we demonstrate that philanthropic institutions are in the business of creating public value. In framing the work of philanthropy more broadly to include the process of public value creation, philanthropic institutions and leaders are challenged to be more strategic not only in their mission‐fulfillment grant‐making with nonprofit organizations but also in the way they stimulate and encourage collaboration, create the “third space” necessary to incubate ideas to transform society, and leverage resources to increase the return on their investments toward system‐wide change. The implications for philanthropic actors and institutions suggest that the strategic contributions they make toward creation of public value are those that go beyond transactional performance measures, such as number of dollars spent or clients receiving services, to include ways that their investments are amplified by meaningful partnerships with nonprofit and other organizations, changed behaviors of institutions and individuals, and transformative public policies.     

Multicollinearity and the value of a priori information

A measure of multicollinearity is defined which is useful in evaluating maintained hypotheses and aiding estimator selection as it suggests when a non-traditional estimator proposed by Bock (1975) is minimax and dominates ordinary least squares. An example is used to illustrate the presented methodology.     

Latino Immigrants,Discrimination and Reception in Columbus,Ohio

Columbus, Ohio has witnessed rapid growth in its Latino population as immigrants settle in the city to access jobs and a generally low cost of living. Immigrants also face discrimination as they settle in Columbus and interact with the city's citizens. In this paper, we note how discrimination plays out in social and economic isolation; a lack of programmes to support the incorporation of Latinos in the city; and state laws that target immigrants. We present results of ongoing ethnographic work with the Latino community in Columbus.     

Adolescents with Gambling Problems: From Research to Treatment

Considerable interest in the area of youth gambling has prompted an increase in empirical investigations examining the correlates associated with youth experiencing severe gambling problems. Based upon the current state of knowledge and our clinical experience, the development of the treatment program for youth with serious gambling problems employed at the McGill University Youth Gambling Research and Treatment Clinic is described. The major tenets, underlying philosophy, and therapeutic processes are presented. A case study is included to illustrate the therapeutic approach. The authors present the need for greater funding for more basic and applied research and the necessity for further scientifically validated treatment and prevention programs.     

A national survey of alcohol screening and referral in college health centers

To determine the extent and nature of alcohol screening and referral services provided by college health centers, the authors conducted a state-stratified, random sampling of 25% of 327 4-year accredited US colleges and universities with health centers. Of the 249 survey respondents, 32% routinely screened students for alcohol use. Urban, public, and large institutions were most likely to screen routinely. Only 11.7% of the sample reported they used standardized instruments, predominantly the CAGE. The health centers used an average of 3.4 referral options, but only 27.5% offered students access to campus programs specifically designed for students who are substance abusers. Findings suggest that the majority of college health centers are not providing routine alcohol screening for students or using standardized screening instruments. In addition, students are often referred to services that may be inappropriate or ineffective in addressing the needs of college drinkers.     

Ticking fast or ticking slow, through Shc must you go?

Circumstantial evidence places the p66 isoform of the adapter protein Shc in a position to mediate the accelerated aging phenotype displayed by mice expressing shortened forms of the tumor suppressor protein p53. We present a model in which p66(shc) may be responsible for integrating signals from the p53 pathway with signals from the insulin-like growth factor-1/Daf pathway in mammals. A full understanding of how interactions between p53 and p66(shc) affect longevity will require the production of animals with mutations in the genes encoding both proteins.