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971.
972.
973.
Weak ties, particularly those to potential employers, play a more important role than strong ties in the immigration of professionals to the United States. I operationalize network strength through the class of admission variable in the Immigration and Naturalization Service's public use data files,Immigrants Admitted to the United States, 1972–1992. I also examine the differential impact of legislative measures on the availability of strong versus weak ties for four groups of professionals: physicians, nurses, engineers and scientists. Not only do weak ties figure heavily on the immigration experiences of professionals, but those impacts affect women differently than men. Professional women rely more heavily on strong ties than on weak ties when compared with males in their respective professions, with the exception of nursing. These findings suggests a need for further study into the migration experiences of professionals as well as more research into how gendered networks develop among immigrant professionals and how those networks influence (either positively or negatively) immigrant adaptation to United States' society.  相似文献   
974.
This not extends T. L. F. Devis's recent investigation of the relationship between tribal affiliation and fertility in Sierra Leone. Controls are introduced for age structure and economic variables. The findings suggest that tribal affiliation does not have much independent influence on fertility after these factors are allowed for.  相似文献   
975.

A survey is given of the use of modern statistical techniques in event history analysis, and in particular in the study of multi‐state life‐tables in demography. Emphasis is placed on the interplay between partial likelihood and nonparametric maximum likelihood based methods, a) when analysing semi‐Markov models or models with repeated spells, and b) in frailty models for inobservable heterogeneity.  相似文献   
976.
977.
Lack of access to potable water and good sanitation is still one of the most challenging public health concerns of the twenty-first century despite steady progress over recent decades. Almost a billion people globally lack access to safe water; over two billion live without adequate sanitation facilities. The challenge is even more daunting for Sub-Saharan Africa where coverage levels for both potable water and sanitation remain critically low. The urgent need to address the issue calls for adequate understanding of the socio-economic dimensions. Using the 2008 Ghana Demographic and Health Survey, we investigated the socio-economic and demographic factors associated with access to potable water and improved sanitation facilities. Our generalized linear models reveal that income, education, household size, and region are significant predictors of improved water and sanitation access. Our discussion and conclusion sections highlight the implications of the study results for water policy formulation and implementation in Ghana, and broadly for other developing countries.  相似文献   
978.
Through a representative sample of 9,100 and 8,755 employees in 2008 and 2010, and a using two-stage structural equation model, this article empirically analyses the multi-dimensional determinants (direct effects) of job quality in Spain. The research concludes that: #1 despite the economic crisis, job quality improved over the analysis period; #2 there was a shift in job quality explanation towards a more complete model with greater preponderance of the dimensions connected with the workplace relationships, work intensity, working conditions and work–life balance in detriment to dimensions connected with the intrinsic job quality and extrinsic rewards. These results suggest the importance of the working environment and social relationships, beyond the quality of the workplace, as important tools of employment public policy to improve labor markets and to overcoming the economic crisis.  相似文献   
979.
980.
Survival bias is a long recognized problem in case–control studies, and many varieties of bias can come under this umbrella term. We focus on one of them, termed Neyman's bias or ‘prevalence–incidence bias’. It occurs in case–control studies when exposure affects both disease and disease-induced mortality, and we give a formula for the observed, biased odds ratio under such conditions. We compare our result with previous investigations into this phenomenon and consider models under which this bias may or may not be important. Finally, we propose three hypothesis tests to identify when Neyman's bias may be present in case–control studies. We apply these tests to three data sets, one of stroke mortality, another of brain tumors, and the last of atrial fibrillation, and find some evidence of Neyman's bias in the former two cases, but not the last case.  相似文献   
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