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.     

Older disabled workers' perceptions of volunteering

The activity of volunteering is readily available to, and undertaken by, able-bodied people in Australia and is recognized as a valuable social pursuit, particularly among citizens of retirement age. Despite the known benefits of volunteering, however, there are few reports of disabled people participating as volunteers and little is understood of their experiences or perceptions of volunteering. The aim of this study was to explore how older workers within supported employment settings perceived the opportunities for and barriers to volunteering. Fourteen people with long-standing impairments participated in this small qualitative study. Overall the participants were positive about volunteering, but noted they might require support to volunteer successfully. Drawing upon the participants' views, recommendations are made for developing training. Disabled workers facing retirement need to be supported to have opportunities for active participation in the community as volunteers if so desired.     

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).     

Unexpected but authentic use of an ethnically–marked dialect

Recent work on language crossing in the U.S. has examined the temporary appropriation of African American Vernacular English by white youth in an effort to participate in the current popularity and prestige of hip–hop culture, or in order to highlight racial boundaries. While such verbal behavior probably encompasses most white use of AAVE, it is not the only way in which whites (or other non–blacks) can use the variety. This paper presents a case study of the language of a 23 year old white female who makes consistent use of many distinctive linguistic features associated with AAVE. I argue that the interaction of ideologies of race, class, localness and language allow her to be considered an ingroup member despite her biographical race. This suggests that there is a tension between academic linguistic theory and actual speaker practice in assigning authenticity to individuals, and I conclude that language ideologies and other forms of qualitative evidence should be taken into account by sociolinguists looking at the link between language and race.     

Infants' Responses to Gender‐Inconsistent Events

Toddlers' knowledge of the stereotyping of traditionally feminine and masculine household activities was examined using the preferential looking paradigm. Seventy‐seven 24‐month‐old infants observed a series of 9 pairs of photographs, each portraying a male and female adult engaged in the same stereotyped or gender‐neutral activity (e.g., ironing, hammering, or reading). Longer looking times were predicted on stimuli inconsistent with gender stereotypes (e.g., looking longer at the man putting on lipstick than at the woman). The results suggested that toddlers have acquired some knowledge of the gender stereotyping of feminine activities by their 2nd birthday.