A modified common factor model for modelling mortality jointly for both sexes

Journal of Population Research - There is an increasing attention on the joint modelling of multiple populations. Populations are related in several ways, such as neighbouring countries, females...     

Heteroscedastic Global Tests that the Regression Parameters for Two or More Independent Groups are Identical

Simulation results are reported on methods that allow both within group and between group heteroscedasticity when testing the hypothesis that independent groups have identical regression parameters. The methods are based on a combination of extant techniques, but their finite-sample properties have not been studied. Included are results on the impact of removing all leverage points or just bad leverage points. The method used to identify leverage points can be important and can improve control over the Type I error probability. Results are illustrated using data from the Well Elderly II study.     

Learning at the edge

This article describes the metaphors persons used to describe their experiences within a three year training project in family therapy. Questions were posed of trainees that had asked them to describe their experiences of training as if they represented the title of a book, movie or journal article. Responses reveal how they construct or ‘story’ their experiences from both a first and second-order cybernetic perspective.     

How Welfare Policies Affect Adolescents' School Outcomes: A Synthesis of Evidence From Experimental Studies

Using data from 8 random assignment studies and employing meta‐analytic techniques, this article provides systematic evidence that welfare and work policies targeted at low‐income parents have small adverse effects on some school outcomes among adolescents ages 12 to 18 years at follow‐up. These adverse effects were observed mostly for school performance outcomes and occurred in programs that required mothers to work or participate in employment‐related activities and those that encouraged mothers to work voluntarily. The most pronounced negative effects on school outcomes occurred for the group of adolescents who had a younger sibling, possibly because of the increased home and sibling care responsibilities they assumed as their mothers increased their employment.     

The Market Provision of Management Services, Information Asymmetries and Service Quality—Some Market Solutions: an Empirical Example

This article examines the problems of information asymmetry associated with the market provision of managerial services. Such problems are heightened by those characteristics which differentiate services from goods. Two unique, and central, characteristics of services, are intangibility and perishability. These create special problems for the market provision of services. In particular they make for difficulties in assessing quality; whereas the producer may know product quality, the buyer often does not. The asymmetry between sellers and buyers is of two types: Adverse selection and moral hazard. Adverse selection occurs when the buyer cannot observe the relevant characteristics of the seller or the conditions under which they work. The problem of moral hazard is the buyer's inability to observe the action taken by the sellers. If these difficulties are not overcome, the market could collapse as companies withdraw and internalize service provision. However, each market has a number of in-built mechanisms which remedy the harmful effects associated with information-related problems. The institutional arrangements which predominate in particular markets are dependent upon the trust-producing mechanisms within those markets. Consequently, market responses to information asymmetries are far from uniform. The argument is illustrated using the example of the executive recruitment industry. In this respect the paper is a highly focused study of those mechanisms which overcome information asymmetries in one service market.     

Dose-Response and Risk Assessment of Airborne Hexavalent Chromium and Lung Cancer Mortality

This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI).     

Female Labor Migrants to Shanghai: Temporary “Floaters” or Potential Settlers?1

Using data on 54,373 migrants from the Fifth Sampling Survey of the Floating Population of Shanghai, this article isolates a group of 32,967 rural labor migrants who hold rural household registrations and whose previous occupations were in agriculture, and focuses on the women among them. The demographic and occupational characteristics of these 9,124 women are described, demonstrating that migration to Shanghai is a highly gendered process, with men and women working in different occupations and sectors. Moreover, important differences are found to exist between unmarried and married female rural labor migrants that indicate that the latter are probably accompanying and working with their migrant husbands. A significant proportion of female “social” migrants also exhibit characteristics that indicate that they are the spouses of male rural labor migrants, bringing to over one third the proportion of rural labor migrants to Shanghai who could be migrating as couples. These couples and their children may be the vanguard in a transition from temporary labor migration to settlement in China's large cities.     

Border Crossings and Diasporic Identities: Media Use and Leisure Practices of an Ethnic Minority

The diaspora of peoples whose origins were in the Indian subcontinent (South Asia) and who are now living in Western countries (especially the U.S. and UK) provides an interesting example of processes of negotiation of new hybrid cultures and identities, using new technologies, such as the Internet, and older technologies like the video player, cable or satellite television, radio, and telephone. These developments may require a revision of the classic sociological picture of assimilation as a zero sum model of acculturation, in which the acculturation of immigrants and their children involves the gradual replacement of their ethnic culture by that of the culture of the host nation. The electronic media, in the context of policies of multiculturalism, may lead to an accentuation of religio-ethnic differences. Contrary to previous assumptions, middle-class immigrants may be more inclined to resist cultural assimilation than their lower-class counterparts.