Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.     

Characteristics of smokeless tobacco use among high school football players as related to type of smokeless tobacco and period of use.

The present study was conducted to assess differences in the behavioral and demographic characteristics of snuff (dip) users as compared to users of chewing tobacco. High School football players (1116) were surveyed concerning their use and perceptions of smokeless tobacco. Adolescent athletes who tried smokeless tobacco were more likely to be white, to use cigarettes, alcohol, and cigars and to have family users than those who never tried. Initial use was highest before the age of fourteen years and was influenced by friends, curiosity and family. Dippers tended to initiate use because of friends, while chewers started because of family users. Users of both dip and chew started primarily because of curiosity. Users of both were more likely to consume greater amounts to alcohol and cigarettes and to smoke cigars and pipes. It appears that the longer smokeless tobacco is consumed, the more likely both dip and chew will be used. Users of smokeless tobacco for more than two years tended to consume more of the product each week, used it for more hours/day, initiated use at an earlier age, and used it more often at school and work than those using it for less than two years. Use of cigars/pipes, consumption of alcohol, and quantity of cigarette consumption increased significantly with longer duration of smokeless tobacco use. Intervention and prevention programs would be helped by understanding differences between users of various smokeless tobacco products and differences related to the duration of use. In addition, further analyses of smokeless tobacco users should study chewers, dippers, and users of both separately.     

Cognitive and behavioral therapies for pathological gambling

The purpose of this paper is to provide an overview of behavioral and cognitive treatment approaches in the management of pathological gambling disorders. Disappointingly, the literature to date contains only one controlled outcome study in which two differing behavioral techniques were compared. Although research in general has focussed on identifying the nature of cognitive distortions in gambling, findings from these studies have not been systematically translated into treatment programs. It is concluded that methodological limitations including small sample size, absence of control groups, multiple concurrent interventions and poorly defined outcome criteria preclude conclusive statements to be drawn regarding the active ingredient of either behavioral or cognitive strategies. The program offered within the Impulse Disorders Research Centre is outlined.The authors wish to gratefully acknowledge the assistance and contribution of Zachary Steel, Research Assistant, in the preparation of this paper.     

First Nations and community economic development: a case study

A training project in a northern Canadian community providedan opportunity to examine participatory planning approachesand the meaning of work in First Nations communities. Focusgroups conducted three years after the unsuccessful interventionof a community economic development (CED) project suggest thatcomplex factors such as lack of support from community leadersand rate of pay for workers determine whether CED is alwaysappropriate in northern, First Nations contexts.     

René Königs beitrag zur Soziologie in Deutschland

Ohne Zusammenfassung Rede zum 100. Geburtstag auf einer Veranstaltung der Stadt K?ln, der René-K?nig-Gesellschaft und des Westdeutschen Rundfunks K?ln am 11. Mai 2006 in K?ln     

Conditioning effect of prior reputation on perception of corporate giving

Prior corporate reputation, one responsibility of a public relations department, affects public perceptions toward corporate philanthropic messages and ultimately affects public attitudes toward the company. Using an experiment that emulates the sort of news consumption individuals normally undertake, participants inferred corporate charitable giving as a mutually beneficial activity when a company had a good reputation (H1a). Participants inferred corporate charitable giving as a self-interested activity when the company had a bad reputation (H1b). Also, public inference (suspicion) successfully mediated corporate prior reputation on public attitude toward the company (H2). Participants showed positive attitude toward the company when they inferred the company had an altruistic motive for charitable giving (H3a). However, participants showed negative attitude toward the company when they inferred the company had a self-interested motive for charitable giving (H3b).     

The humorous construction of disability: 'stand-up' comedians in the United States

We examine how stand-up [sic] comedy constructs, circulates, perpetuates and/or disrupts stereotypical images of disabled persons in the United States. We use disabled people, rather than people-first language, to remind readers that disability is an ill-defined, culturally imposed attribute. Although humor is culturally specific, we draw on works of an international cadre of humanities scholars and social scientists to ground our analyses. We conclude that disability humor constitutes an emerging, liberatory art form. Disabled and non-disabled comedians elicit thought-provoking laughter and present disability as an interesting way to live. However, disabling humor still perpetuates stereotyping and isolation.     

Liability in child welfare

Child welfare workers and agencies are vulnerable to lawsuits. Recent court rulings have more clearly defined the liability of workers. The distinguishing variable is custody. Children injured while in the custody of the state are entitled to sue for damages. Children injured by their parent, even if under the supervision of a child welfare agency, are not entitled to claim a violation of their 14th Amendment rights. These cases are reviewed and strategies designed to minimize vulnerability are offered.