The effect of mixing-distribution misspecification in conjugate mixture models

Parametric mixture models are commonly used in the analysis of clustered data. Parametric families are specified for the conditional distribution of the response variable given a cluster-specific effect, and for the marginal distribution of the cluster-specific effects. This latter distribution is referred to as the mixing distribution. If the form of the mixing distribution is misspecified, then Bayesian and maximum-likelihood estimators of parameters associated with either distribution may be inconsistent. The magnitude of the asymptotic bias is investigated, using an approximation based on infinitesimal contamination of the mixing distribution. The approximation is useful when there is a closed-form expression for the marginal distribution of the response under the assumed mixing distribution, but not under the true mixing distribution. Typically this occurs when the assumed mixing distribution is conjugate, meaning that the conditional distribution of the cluster-specific parameter given the response variable belongs to the same parametric family as the mixing distribution.     

On cross‐validation of Bayesian models

The authors examine several aspects of cross‐validation for Bayesian models. In particular, they propose a computational scheme which does not require a separate posterior sample for each training sample.     

In Defense of a Utilitarian Business Ethic

In this article, I suggest and support a utilitarian approach to business ethics. Utilitarianism is already widely used as a business ethic approach, although it is not well developed in the literature. Utilitarianism provides a guiding framework of decision making rooted in social benefit which helps direct business toward more ethical behavior. It is the basis for much of our discussion regarding the failures of Enron, Worldcom, and even the subprime mess and Wall Street Meltdown. In short, the negative social consequences are constantly referred to as proof of the wrongness of these actions and events, and the positive social consequences of bailouts and other plans are used as ethical support for those plans to right the wrongs. I believe the main cause of the neglect of the utilitarian approach is because of misguided criticisms. Here, I defend utilitarianism as a basis for business ethics against many criticisms found in the business ethics literature, showing that a business ethics approach relying on John Stuart Mill's utilitarianism supports principles like justice, is not biased against the minority, and is more reasonable than other views such as a Kantian view when dealing with workers and making other decisions in business. I also explain utilitarian moral motivation and use satisficing theory to attempt to defend utilitarian business ethics from questions raised regarding utilitarian calculus.     

Automated statistical methods for measuring the strength of block ciphers

A block cipher is one of the most common forms of algorithms used for data encryption. This paper describes an efficient set of statistical methods for analysing the security of these algorithms under the black-box approach. The procedures can be fully automated, which provides the designer or user of a block cipher with a useful set of tools for security analysis.     

Western voodoo: providing mental health care to Haitian refugees

This article described certain aspects of Haitian life, voodoo and its role in Haitian society, the quality and quantity of psychiatric and mental health care for Haitians in Haiti, and suggestions for providing appropriate mental health care to Haitian refugees in the United States. Conway and Buchanan (1985) described what has helped Haitian refugees adapt in the transition to life in the United States: the strengths from their cultural heritage, such as fortitude; perseverance in the most arduous circumstances; deep religious faith; high self-respect; reliance on the extended family; and the tradition of sharing. Building on these assets may assist Western mental health-care providers in offering culturally sensitive mental health care to Haitians.     

Educational efforts in the implementation of rural family planning programs in East Pakistan

The pilot family planning studies reported in this paper were conducted in a rural area adjacent to the city of Dacca in East Pakistan. It reports the preliminary findings of action-research in the implementation of educational efforts to reach rural villagers of a developing country.Preliminary analyses of the records identify two significant educational problems: (1) most of the villagers (85-90 percent of the couples) who initially accepted contraceptives do not truly adopt and become continuing users and (2) the continuing users (10-15 percent of the initial users) are generally characterized by large families. (Later data show an even lower percentage of continuing users.)The field activities in the development of various educational approaches to family planning are described. Three separate geographic areas (from 15,000 to 20,000 population) were each approached in a different way, varying in the number and educational qualifications of the workers and in the degree of involvement of village leadership. Preliminary analyses of field records indicate that these variations of approach apparently have little effect on the percentage of the population willing to accept contraceptive supplies.It is the opinion of the writers that more intensive educational efforts are necessary at the village level to develop social support for continuing use of contraception and to gain adoption of contraception by younger married couples primarily for spacing of births.The impact of introduction of the IUCD in populations where condoms and foam tablets have been available for one to two years has also been reported. Preliminary findings indicate that the IUCD encourages adoption by previous non-users and may increase the over-all percentage of contraceptive users.     

CharacteriStics and utilization of midwives in a selected rural area of East Pakistan

The purpose of this study was to obtain information about the utilization of midwives (dais) by village women and to learn more about the characteristics and practices of those dais. Two interview schedules were prepared. The first was used to interview 632 village women to determine who performed or assisted with their last two deliveries. The second was used to obtain information from 21 dais.The results of the first phase may be summarized as follows: (a) 38 per cent of the women were delivered by relatives; (b) 33 per cent of the women delivered their own children; (c) 14 per cent were delivered by neighbors; (d) 6 per cent were delivered by dais; (e) 2 percent were delivered in hospitals; and (f) the remaining 7 per cent were accounted for by several minor categories.The results of the interviews with dais are summarized as follows: (a) they are mainly widows and older women; (b) they have no formal training; (c) they work for friends, neighbors, and relatives and receive a sari as compensation; (d) they cannot handle complicated deliveries; (e) they deliver 3-4 children a year; (f) their sterilizing procedures depend upon soap, water, and folk beliefs; (g) most think midwifery is a worthwhile service; (h) about one-half have a general understanding of the reproduction process; (i) most do not know how to prevent conception; and (j) about half think that it is a good idea to participate actively in a family planning program.