Testing for a trend in exponential means: A two-moment approximation to the null distribution of the likelihood-ratio statistic

The likelihood-ratio test statistic for testing homogeneity of exponential means with an ordered alternative has a rather complex null distribution. Expressions for the mean and variance of its null distribution are derived, and the accuracy of a two-moment chi-squared approximation is studied. The coefficients needed to implement the approximation are tabled. The application of these results in testing for a constant versus a nondecreasing intensity in a nonhomogeneous Poisson process is also discussed.     

A Bayesian method of sample size determination with practical applications

Summary.  The problem motivating the paper is the determination of sample size in clinical trials under normal likelihoods and at the substantive testing stage of a financial audit where normality is not an appropriate assumption. A combination of analytical and simulation-based techniques within the Bayesian framework is proposed. The framework accommodates two different prior distributions: one is the general purpose fitting prior distribution that is used in Bayesian analysis and the other is the expert subjective prior distribution, the sampling prior which is believed to generate the parameter values which in turn generate the data. We obtain many theoretical results and one key result is that typical non-informative prior distributions lead to very small sample sizes. In contrast, a very informative prior distribution may either lead to a very small or a very large sample size depending on the location of the centre of the prior distribution and the hypothesized value of the parameter. The methods that are developed are quite general and can be applied to other sample size determination problems. Some numerical illustrations which bring out many other aspects of the optimum sample size are given.     

What is Peace Psychology the Psychology of?

Peace psychology emerged as a distinct area of research and practice during the Cold War, when the preeminent concern was the prevention of nuclear war. Now global in scope, the focal concerns of peace psychologists are nuanced by geohistorical contexts and the distinction between episodic violence and structural violence, the latter of which also kills people, albeit slowly through the deprivation of basic need satisfaction. Accordingly, the focal concerns of contributors to this issue vary depending on geohistorical context: some being primarily concerned with patterns of behavior and cognition involved in the prevention of violent episodes and others with the amelioration of structural violence. A systems perspective is used as a framework for integrating episodes and structures of violence and peace. Articles emphasizing "systemic violence" demonstrate the interplay between structures and episodes of violence. Articles on "systemic peacebuilding" examine intergroup contact, the nonviolent management of conflict, and movement toward socially just structures, thereby yielding an increase in cooperative and equitable relationships across levels, from interpersonal to intergroup.     

The abused and neglected foster child: Determinants of emotional conflict and oppositional behavior

Behavioral and emotional problems have been observed in emotionally vulnerable children in foster care under certain circumstances. A common pattern involves the unpredictable appearance of a previously absent or unavailable natural parent. Such an occurrence precipitates the reawakening of the child's ambivalent feelings toward both natural and foster parents as well as their fears of abandonment. This frequently leads to behavior that is oppositional and difficult to manage. If the foster parents find the child's behavior unmanageable, and if they are not provided with appropriate professional support during this difficult period, a crisis often follows that precipitates the child's removal from the foster home. Individual, familial, and systemic contributions to this dilemma are discussed. This article emphasizes the origins and nature of the intrapsychic dilemma faced by these children. Particular emphasis is placed on the manifestations of a conflict of loyalty, in the child, and its relationship to the oppositional behavior of these children in foster care. Additional considerations include the impact of inconsistent parenting, abuse and neglect by the natural parents, the assumption of a parental role by the child and a concomitant renunciation of the child's dependency needs, as well as an examination of the role of the foster parent's fantasy of what it will be like to parent a traumatized child.     

The public library system. Social services resource for the geriatric population

The public library system is targeting the geriatric population and instituting programs to meet informational and recreational needs. From retirement planning, visual aids, and screening, to accessing library material to the elderly, the public library system attempts to meet the challenge of providing service to this special population. Although not a formal group, the library has inherent therapeutic effects that benefit the elderly who participate in their programs. The clinician would be advised to take advantage of these various programs. Because each local and regional center will offer different programs, calling a local library is the most effective way to find out what a specific public library system has to offer. Nurses may also consider joint efforts to initiate programs in their library systems to better meet the population's needs.     

The politic,philosophy and practice of OR—A personal view of the issues

It is almost 50 years since Sir Henry Tizzard created the group of scientists in RAF Fighter Command who were to coin the term ‘Operational Research’. The group still exists, though its work, and the work of other defence OR groups, has changed from solving acute operational problems by the extrapolation of observed data, to an attempt at predicting the outcome of policy choices that are beyond experience. Inevitably this has forced OR further into a political arena. Yet most OR practitioners are scientists used to investigating apolitical and benign nature. In this paper the author gives a personal view of what he believes OR is trying to achieve, what practical problems and pressures have to be faced and attempts to give guidance on how to proceed.     

Racial concentration and segregation across U.S. counties, 1950–1980

By presenting race-specific population concentration indexes for U.S. counties for the 1950-1980 period, this paper updates and extends previous analyses of 1900-1974 patterns of population concentration by Duncan et al. (1961) and Vining and Strauss (1977). Declines in population concentration persisted through 1980 only among the white population. Blacks continued to experience increases in population concentration between 1970 and 1980. These racially divergent patterns of concentration in the 1970s have translated into increases in segregation between blacks and whites across U.S. counties.     

Transfer programs and aggregate household formations

The number of households in the United States increased by over fifty percent in the 1960s and 1970s, nearly double the rate of population growth. Part of the increase is explained by the movement of large cohort groups of the population into prime household-forming age categories, but higher headship rates also contribute. Age-specific headship rate increases result from non-demographic factors, and this paper focuses on the role of government transfer payment programs. Specifically considered are Social Security, Aid to Families with Dependent Children, and Food Stamps. These programs are found to have accounted for as many as 4 million net household formations between 1961 and 1984. The findings have implications for expected households formations in the 1990s.     

Absence behaviour, turnover and disability: A study among city bus drivers in the Netherlands

Absenteeism, turnover and disability, and relationships between them have been studied among city bus drivers in the Netherlands. The theoretical framework for the study was a cumulative process model of work and health. Absenteeism among these drivers was two to three times as high as the national average, while the risk of disablement was more than twice as high as the risk for male Dutch civil servants in general. Bus drivers who had to leave their job for medical reasons did so at a younger age than other groups of civil servants. The main conditions leading to disablement related to the back, tendons and joints (35%), mental disorders (35%) and cardiovascular diseases (12%). It was shown that long-term absenteeism is a strong precursor of future disability. The research suggests a work-related process of progressive deterioration of health and well-being over a reasonably long period of time. Driving city buses seems to be an occupation with high risks for health and well-being.