Finite mixture models with concomitant information: assessing diagnostic criteria for diabetes

The World Health Organization (WHO) diagnostic criteria for diabetes mellitus were determined in part by evidence that in some populations the plasma glucose level 2 h after an oral glucose load is a mixture of two distinct distributions. We present a finite mixture model that allows the two component densities to be generalized linear models and the mixture probability to be a logistic regression model. The model allows us to estimate the prevalence of diabetes and sensitivity and specificity of the diagnostic criteria as a function of covariates and to estimate them in the absence of an external standard. Sensitivity is the probability that a test indicates disease conditionally on disease being present. Specificity is the probability that a test indicates no disease conditionally on no disease being present. We obtained maximum likelihood estimates via the EM algorithm and derived the standard errors from the information matrix and by the bootstrap. In the application to data from the diabetes in Egypt project a two-component mixture model fits well and the two components are interpreted as normal and diabetes. The means and variances are similar to results found in other populations. The minimum misclassification cutpoints decrease with age, are lower in urban areas and are higher in rural areas than the 200 mg dl^-1 cutpoint recommended by the WHO. These differences are modest and our results generally support the WHO criterion. Our methods allow the direct inclusion of concomitant data whereas past analyses were based on partitioning the data.     

Suggestions for management training of residents

In addition to having medical expertise, physicians must possess managerial skills to deal with the ever-changing business environment of the practice of medicine. This article addresses the need for management training of physicians and calls for management training during residency and medical school. It also describes one residency program's efforts to provide comprehensive management training to its residents in pathology.     

International labour migration statistics in Asia: an appraisal

"The present paper attempts a critical review of the data systems of seven major labour-exporting countries--Bangladesh, India, Indonesia, Pakistan, Philippines, Sri Lanka and Thailand--which account for over 90 per cent of labour outflows from Asia....Data...are discussed under separate sections focusing on limitations as well as potential for further exploitation.... For all countries reviewed here, these data significantly understate total labour outflows, and the magnitude of the error seems to vary between countries and reflect both differences relating to the coverage and efficiency of the approval and monitoring procedure. This throws serious doubts on the appropriateness of official outmigration series for cross country comparison. Frequent changes in reporting procedures also make for discrete changes and spurious shifts in data which render trend analysis quite hazardous." (SUMMARY IN FRE AND SPA)     

Bequests as a heir "disciple device."

This paper develops a model ofinter vivos gifts and bequests in a setting of moral hazard and adverse selection. Altruistic parents do not perfectly know how much effort their children make to earn their living, nor do they know their true level of ability.Inter vivos gifts take place prior to the realization of the children's earnings whereas at the moment of bequests, parents do observe them. We show that an optimal transfer policy generally uses a mix ofinter vivos gifts — deemed as more efficient — and bequests — deemed as more redistributive.We are thankful to Allessandro Cigno, Jacques Cremer, Claude d Aspremont and anonymous referees for their comments.Responsible editor: Alessandro Cigno     

Why does cancer cluster?

What do Florida sunbathers, midwestern farmers, rural black men, and Long Island women have in common? They all have higher-than-average risks for certain cancers. Researchers know that cancer clusters are usually caused by several factors. As cancer becomes America's leading cause of death, the public will be keenly interested in sorting out the causes and reducing the risks.     

Income expectations,rural-urban migration and employment in Africa

This article develops a theoretical framework explaining the influence of economic conditions on rural-urban migration in tropical Africa. The model explains the continued process of migration despite high levels of urban unemployment. A lengthy discussion is devoted to short-, intermediate-, and long-term policies for relieving the urban unemployment problem. It is argued that efforts must be made to reduce the differences between the expectation of urban income and real rural income. No one single policy will slow rural-to-urban migration. The author suggests policies that would eliminate factor-price distortions, restrain urban wages, redirect development toward concentrated and comprehensive programs of rural development, resettle and repatriate unemployed urban migrants, and establish capital-goods industries. The capital-goods industries would develop labor-intensive technologies for agriculture and industry. The theoretical model assumes that migrants make decisions about moving on the basis of an expected income and the expectation of an urban job. It is argued that the urban-rural income differences and the probability of securing an urban job determine the rate and extent of rural-urban migration in Africa. If the migrant has a low probability of finding regular wage employment in the short term, but expects the probability to increase over time, the migrant would make a rational decision to migrate. Policies that operate solely on urban labor demand are considered unlikely to reduce urban unemployment. This model better estimates the shadow prices of rural labor.     

Migration and its risks

"This essay applies the theories of Ulrich Beck...to the politics of migration in Germany. In particular, the essay focuses on Beck's notion of the waning influence, indeed even relevancy, of science and scientists regarding postmodern risk phenomena. The essay argues that migration to Germany can be understood as a Beckian risk phenomenon, helping to explain the decreasing influence of social scientists over the politics of migration in the Federal Republic."     

The majority legal status of women in southern Africa: implications for women and families

Women in many countries of southern Africa do not have majority status or have only recently gained this right. Majority status grants individuals adult legal status and the right to bring matters to court, own and administer property, have legal custody of children, and contract for marriage. This article summarizes the legal status of women in Botswana, Lesotho, South Africa, Swaziland, Zambia, and Zimbabwe. Lack of majority status contributes to the ongoing risk of poverty for women and makes them overly dependent on men. Compounding the situation in these countries is the presence of a dual legal system. Improving the situation of women and their families involves targeting changes in the legal system, influencing implementation of laws, educating women about their rights, and giving women needed support to seek their legal rights. The legal status of women must be viewed in the context of historical changes in the economic, educational, political, and cultural developments of society.The research for this paper was conducted during her previous faculty affiliation with the University of Michigan, School of Social Work. Her research interests include the impact of social change on women and families, rural mental health services, and health and mental health linkages. She received her Ph.D. from Rutgers University and her M.S.W. from the Columbia University School of Social Work.Her research interests are gender, work and family, culture and power, social transformations in rural and peri-urban communities, critical education, women and community politics, history of women, family and kinship issues, and community-based program development and evaluation. She received her M.S.W. from Dalhousie University, Halifax.     

An Exploration of the Meaning and Consequences of Workaholism

Although much has been written aboutworkaholism, rigorous research andtheoretical development on the topic is in its infancy.We integrate literature from multiple disciplines andoffer a definition of workaholic behavior. We identify three types ofworkaholic behavior patterns: compulsive-dependent,perfectionist, and achievement-oriented workaholism. Apreliminary model is proposed; it identifies potential linkages between each type of workaholismpattern and important outcomes such as performance, joband life satisfaction, and turnover. Specificpropositions for future research are articulated. Weconclude that, depending on the type of workaholicbehavior pattern, workaholism can be good or bad, andits consequences may be experienced or evaluateddifferently by individuals, organizations, and societyat large. Researchers and managers should avoidmaking judgments about the positive or negative effectsof workaholism until more carefully controlled researchhas been published.