Model Selection and Regression t-Statistics

It is shown that dropping quantitative variables from a linear regression, based on t-statistics, is mathematically equivalent to dropping variables based on commonly used information criteria.     

Contextualizing Business Ethics: Anomie and Social Life

The objective of this paper is to explore howthe current interest in Business Ethics can be locatedwithin an analysis of contemporary society which takesinto account the prevalence of moral uncertainty along with the concomitant desire to(re)establish some form of normative order. As such,Business Ethics may be seen as a socially constructedfield of study which reflects broaderchanges and controversies within society. Yet as a body of knowledge,Business Ethics articulates epistemological doubts. Twodistinctive themes in Business Ethics discourse areconsidered — the modernist/rationalist and thepostmodernist/relativist. It is argued that in different ways, each canbe seen as both an expression of, and a reaction to, theincreasing incidence of anomie in society. Theimplications for organizational practices are thenconsidered through the example of Corporate Codes ofEthics and the problem of establishing consensus wherethe grounds for any claim to moral authority areproblematic.     

Investigating the Dynamics of Migration and Health in Australia: A Longitudinal Study

There have been few longitudinal studies investigating the immigrant health and changes in their health with longer residency in the host country. Additionally, the pathways and mechanisms by which transition of health over time occurs are poorly understood, limiting the ability to implement policies that will result in improved health for all, including immigrants. We assessed differences in health outcomes among foreign-born people from English speaking countries and non-English speaking countries relative to native-born Australians over a 10-year period using a large representative longitudinal dataset. We also explored English language proficiency, socio-economic factors and health behaviour factors as possible mechanisms through which health outcomes change over time post-migration. Conventional multilevel mixed and hybrid regression models were used to evaluate health outcomes in 9558 native-born and 3067 foreign-born people from the Household, Income and Labour Dynamics in Australia survey. There were clear differences in physical health, mental health and self-assessed health between foreign-born subgroups in comparison with native-born Australians. Foreign-born people from English speaking countries typically had a health advantage relative to native-born people, and foreign-born people from non-English speaking countries had a health disadvantage with respect to native-born people for all health outcomes. There was no evidence that these differences changed by duration of residence except for self-assessed health amongst foreign-born people from non-English speaking countries when duration of residence exceeded 20 years. English language proficiency mediated the relationship between duration of residence and health for foreign-born people from non-English speaking countries.     

Second‐order bias‐corrected AIC in multivariate normal linear models under non‐normality

This paper deals with a bias correction of Akaike's information criterion (AIC) for selecting variables in multivariate normal linear regression models when the true distribution of observation is an unknown non‐normal distribution. It is well known that the bias of AIC is $O(1)$ , and there are a number of the first‐order bias‐corrected AICs which improve the bias to $O(n^{-1})$ , where $n$ is the sample size. A new information criterion is proposed by slightly adjusting the first‐order bias‐corrected AIC. Although the adjustment is achieved by merely using constant coefficients, the bias of the new criterion is reduced to $O(n^{-2})$ . Then, a variance of the new criterion is also improved. Through numerical experiments, we verify that our criterion is superior to others. The Canadian Journal of Statistics 39: 126–146; 2011 © 2011 Statistical Society of Canada     

Socio-economic inequalities in mortality for Asian people: New Zealand Census-Mortality Study, 1996–2004

Journal of Population Research - This study examines the association of socio-economic factors with mortality for the Asian population, and compares with those of the European/Other group....     

Negotiating transnational ambivalence: how ageing parents grapple with family separation across time

ABSTRACT

This article uses older parents of parachute kids as an example to explore the ways in which the heads of transnational households assess intergenerational intimacy at a later stage of their life trajectories. I argue that transitioning to a later life stage motivates or even demands older parents reorient their perspectives on the separation from their children overseas. Specifically, I offer the concept of transnational ambivalence to analyse the processes whereby older parents grapple with the meaning of being physically separated from their children. This study demonstrates how the interplay between extended family separation and human ageing provokes complex feelings and emotions among parents. In addition, this research chronicles the factors that explain the variation in parental ambivalence. In so doing, this article contributes to the literature on transnational families by illuminating the temporal reflexivity of parents ‘left behind’.     

Mountain chickadees adjust songs,calls and chorus composition with increasing ambient and experimental anthropogenic noise

Vocal plasticity may allow birds to reduce masking effects of noise pollution arising from urbanization. Mountain chickadees (Poecile gambeli) use both songs and calls during the dawn chorus, which vary in masking susceptibility. Thus, increasing song or call frequency, or switching between vocalization types are all potential mechanisms to reduce masking during fluctuating noise conditions. Further, prior experience with noise pollution may be a necessary precursor to allow birds to alter signals in response to sudden noisy conditions. To determine how mountain chickadee songs, calls, and chorus composition are affected by noise, we recorded 55 males across gradients of local ambient noise and habitat urbanization in three cities in British Columbia, Canada. Of these individuals, 31 were also exposed to 5-min experimental noise treatments. Habitat urbanization was quantified through a continuous index reflecting properties of urbanized areas. Only song frequency increased with local ambient noise, and this effect varied regionally. In response to experimental noise exposure, males increased the frequency of their calls (but not of their songs), and varied their use of songs vs. calls. Interestingly, this response was dependent on local ambient noise levels: males in noisy areas shifted to using relatively more songs, whereas males in quiet areas shifted to using relatively more calls. These findings may suggest that although mountain chickadees are capable of adjusting their vocalizations, choosing a response which can lead to masking release may require prior exposure to high levels of ambient noise.     

Urban environments are associated with earlier clutches and faster nestling feather growth compared to natural habitats

Urbanization creates new habitats with novel benefits and challenges not found in natural systems. How a species fares in urban habitats is largely dependent on its life history, yet predicting the response of individual species to urbanization remains a challenge. While some species thrive in urban areas, others do poorly or are not present at all. Mountain chickadees (Poecile gambeli) are year-round residents of montane regions of western North America. Commonly found in higher-elevation coniferous forests, these birds can also be found in urban areas where they will regularly visit bird feeders and nest in nest boxes. We monitored mountain chickadees nesting along a habitat gradient, from natural habitat to suburban areas, to determine if the degree of urbanization was associated with: clutch size and success; nestling growth rates; or variation in parental size and age. Females nesting in urbanized areas initiated clutches earlier in the breeding season than those in natural areas, but neither fledging success nor the rate of nestling mass-change differed between habitats. Nestling feather growth-rate increased with later first egg dates in both habitats, and the magnitude of this increase was greatest in urban habitats. We found no difference in the proportion of first-time breeders versus experienced breeders between habitat types, nor any differences in male or female mass or size. Our results indicate no detriment to nesting in urban habitats, suggesting mountain chickadees are able to adapt to moderate urbanization much like other members of the Paridae family.     

Changes in health-related quality of life in elderly men after 12 weeks of strength training

Background

Muscular strength is associated with functional ability in elderly, and older adults are recommended to perform muscle-strengthening exercise. Understanding how improved muscle strength and -mass influence general and specific domains of quality of life is important when planning health promotion efforts targeting older adults. The aims of the present study were to describe changes in health-related quality of life (HRQOL) in older men participating in 12 weeks of systematic strength training, and to investigate whether improvements in muscle strength and muscle mass are associated with enhancements in HRQOL.

Methods

We recruited 49 men aged 60–81 years to participate in an intervention study with pre-post assessment. The participants completed a 12-week strength training program consisting of three sessions per week. Tests and measurements aimed at assessing change in HRQOL, and changes in physical performance (maximal strength) and physiological characteristics. HRQOL was measured using the 12-item short-form survey (SF-12). Muscle mass was assessed based on changes in lean mass (leg, trunk, arm, and total), and strength was measured as one-repetition maximum in leg extension, leg press, and biceps curl.

Results

Two of the eight HRQOL SF-12 scores, role physical and general health, and the physical component summary scores, increased significantly during the intervention period. Small significant positive correlations were identified between improvements in muscle strength, and better physical and social function. Moreover, a significant increase in total muscle mass was seen during the intervention period.

Conclusions

The positive, findings from this study would suggest that systematic strength training seems to be a beneficial intervention to improve HRQOL, muscle strength and muscle mass in older men.