A principal curve (Hastie and Stuetzle, 1989) is a smooth curve passing through the middle of a distribution or data cloud, and is a generalization of linear principal components. We give an alternative definition of a principal curve, based on a mixture model. Estimation is carried out through an EM algorithm. Some comparisons are made to the Hastie-Stuetzle definition. 相似文献
"This article revises the Coale-Trussell method for analyzing data from the World Fertility Survey by proposing and testing alternative log-linear and log-multiplicative models. The models, in one form or another, represent the structural constraint underlying the Coale-Trussell method on the variation in the age pattern of human fertility. With a Poisson distribution assumption for the number of births, several parameters of the models are simultaneously estimated via maximum likelihood. It is shown that the new approach can be adopted whenever fertility limitation is compared across multiple populations or subpopulations." 相似文献
This research note briefly outlines International Labour Organization concerns about return migration in developing countries, research being done in the field, and activities in related fields. Attention is being focused on the following topics and areas of study: 1) recommendations and conventions which cover workers generally and migrant workers particularly; 2) measures to avoid the departure of skilled workers from developing countries; 3) special problems encountered in improving migrant professionals' working conditions; 4) developing a central pool of information on labor markets and employment at the international level; 5) bilateral or multilateral migration agreements to optimize the flows of health personnel, scientific workers, engineers, and high level technicians, protecting their rights, and facilitating their reintegration into the country of origin; 6) creating a compensation scheme for skill outflows and training substitutes to fill the gaps left behind by migration; 7) classifying migratory policies adopted by developing countries; 8) reattraction of needed skills to developing countries of origin; 9) transfer of know-how through expatriate nationals; 10) labor reinsertion patterns of migrants returning to Greece, Italy, Portugal, and Spain; 11) Socioeconomic reintegration of migrants returning to Pakistan and Uruguay; and 12) Sri Lanka's experience with self-employment schemes for returned migrants. 相似文献
The author analyzes international migration patterns of Caribbean populations, with particular attention to the persistence of significant return flows. A typology of migration in the region is presented, which includes categories of transients or shuttle migrants and settlers or long-stay migrants. Skill or occupational changes, principal remittances, and migration objectives of each group are summarized. The social, economic, and policy implications of international circulation in the Caribbean are considered. (SUMMARY IN FRE AND SPA) 相似文献
Puerto Rican migration to the US has been a more or less continuous process since 1917. The perspective of viewing return migration as a circulation process suggests that there are entries, exits, and reintergration into the metropolitan labor market. This study explores the circulatory movements of Puerto Rican families, events that influence the adaptation process when returning to Puerto Rico, and cultural identity aspects. Data collected by means of 2 research instruments that were administered to the respondents simultaneously were used: 1) a life history matrix and 2) an open-ended questionnaire. These interviews outlined the principal problems of adaptation as mentioned by the circulating migrants. The most difficult problems to adjust to were economic and employment (58%), followed by social acceptance (23%), education (17%), and language (15%). Transportation, medical services, and recreational facilities were also problems mentioned as being significant. It is expected that a great majority of migrant laborers will go to live in immigrant residential locations in large US cities. It is also expected that these migrants will meet with certain value conflicts by living in urban ghettos. These families will have serious difficulties finding economic stability and will possibly consider migrating once again as an alternative to their social reality. This study illustrates that: 1) the migrants return in family groups; 2) they face discriminatory problems in employment agencies and schools; 3) they look forward to a formal education as a means of social mobility; 4) they identify themselves with values, habits, and Puerto Rican traditions; and 5) they value the quality of life in Puerto Rico. 相似文献
Now that evaluators have been sensitized to the importance of moral and ethical issues in their work, it is time to move beyond generalities and examine the moral and ethical implications of specific evaluation models in specific settings. This paper proposes a framework that can be used to examine moral and ethical dimensions of evaluation and illustrates it by analyzing a selected model of mental health evaluation. Such a systematic identification of moral issues can improve evaluation practice both proactively, by shaping the training of evaluators, and retrospectively, by contributing to meta-evaluation. 相似文献
Since 1970 the Philippine population program has made considerable achievements in its effort to curb the country's high fertility rate. The program presently aims to attain a population growth rate of 2.0% in 1992 and eventually achieve replacement fertility for the country by the year 2000. To achieve these rates, the program has set into motion the so-called "high scenario" targets of greatly increasing the overall rates of use-effectiveness of program methods of contraception. The program continues to be guided by policies implemented since its start, as well as by new ones in resonse to recent developments. Though the program continues to receive funds from international donors, the Philippine government's share in the funding has steadily increased. 相似文献
During the past decade, the international statistical community has made several efforts to develop standards for the definition, collection and publication of statistics on international migration. This article surveys the history of official initiatives to standardize international migration statistics by reviewing the recommendations of the International Statistical Institute, International Labor Organization, and the UN, and reports a recently proposed agenda for moving toward comparability among national statistical systems. Heightening awareness of the benefits of exchange and creating motivation to implement international standards requires a 3-pronged effort from the international statistical community. 1st, it is essential to continue discussion about the significance of improvement, specifically standardization, of international migration statistics. The move from theory to practice in this area requires ongoing focus by migration statisticians so that conformity to international standards itself becomes a criterion by which national statistical practices are examined and assessed. 2nd, the countries should be provided with technical documentation to support and facilitate the implementation of the recommended statistical systems. Documentation should be developed with an understanding that conformity to international standards for migration and travel statistics must be achieved within existing national statistical programs. 3rd, the call for statistical research in this area requires more efforts by the community of migration statisticians, beginning with the mobilization of bilateral and multilateral resources to undertake the preceding list of activities. 相似文献
Nathan Glazer Ethnic Dilemmas Harvard, Harvard University Press. 1985
Giddens, Anthony The Constitution of Society, Berkeley, University of California, 1985, pp.XXXVII, 402. Notes, glossary, diagrams, bibliographic notes and index.
Jeremy Rifkin Declaration of a Heretic. Boston. London, Melbourne and Henley, Routledge and Kegan Paul, 1985, pp.X,140.
Ted Benton The Rise and Fall of Structural Marxism: Althusser and his Influence, New York, St.Martin's Press, 1984, pp. VII,259.
Raymond L. Garthoff Détente and Confrontation Washington, The Brookings Institution, 1985, pp.XVI,1126.
Joseph J. Collins The Soviet Invasion of Afghanistan. A Study in the Use of Force in Soviet Foreign Policy, Massachusetts/Toronto, D.C. Heath and Company/Lexington, 1986, pp. XV, 195.
Jan Shipps Mormonism: The Story of a New Religious Tradition, Chicago, University of Illinois Press, 1985, pp.211.
Robert Jay Lifton Home from the War: Vietnam Veterans: Neither Victims nor Executioners, New York, Basic Books, 1985, pp.478 相似文献