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     

An Application of Expectancy Theory to Explain a Manager's Intention to Use a Decision Support System

A continuing gap exists between the capabilities of sophisticated computer-based information systems and the extent to which these systems are used by individuals. Studies which have examined the relationship between system utilization and various user, system, implementation, and organizational variables have provided few consistent findings. A new approach to this topic is suggested by a recent study by Davis, Bagozzi, and Warshaw [11], which indicates that individuals' intentions to use a system determine subsequent use. A large body of psychology-based research also supports this relationship between behavioral intentions and subsequent behavior. This study employs expectancy theory, which has often been used to examine behavioral intentions, to explain managers' intentions to use a decision support system (DSS). The results imply that the variables of the expectancy force model are determinants of a manager's behavioral intentions to use a DSS, and the variables of the expectancy valence model are determinants of the attractiveness of using a DSS to a manager.     

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....     

The Extraction of Nonverbal Behaviors: Using Video Images and Speech-Signal Analysis in Dyadic Conversation

This study examined the validity and possible utility of a new procedure for the extraction of nonverbal behaviors from dyadic conversation. Three methods were used to extract nonverbal behaviors (i.e., hand gestures, adaptors, and utterances). A novel automated method employing video images and speech-signal analysis software programs was compared to the more traditional coding and behavioral rating methods. The automated and coding methods provided an objective count of how many times a target behavior occurred, while behavioral ratings were based on more subjective impressions. Although there was no difference between the automated and coding methods for hand gestures, the coding method using an event recorder yielded marginally significantly more instances of adaptors and utterances as compared to the software programs. Measures of each nonverbal behavior were positively correlated across the different methods. In addition, interpersonal impressions of each speaker were rated by both observers and conversational partners. Although R ² was lower than for the coding/behavioral rating methods, nonverbal behaviors extracted using the software programs significantly predicted familiarity and activeness ratings from both observer and partner points of view. These results support the validity and possible utility of the software-based automated extraction procedure.     

An age–period–cohort analysis of cancer incidence among the oldest old,Utah 1973–2002

We used age–period–cohort (APC) analyses to describe the simultaneous effects of age, period, and cohort on cancer incidence rates in an attempt to understand the population dynamics underlying their patterns among those aged 85+. Data from the Utah Cancer Registry (UCR), the US Census, the National Center for Health Statistics (NCHS), and the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) programme were used to generate age-specific estimates of cancer incidence at ages 65–99 from 1973 to 2002 for Utah. Our results showed increasing cancer incidence rates up to the 85–89 age group followed by declines at ages 90–99 when not confounded by the separate influences of period and cohort effects. We found significant period and cohort effects, suggesting the role of environmental mechanisms in cancer incidence trends between the ages of 85 and 100.     

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.

     

A UNIFIED FRAMEWORK FOR MODELLING WILDLIFE POPULATION DYNAMICS†

This paper proposes a unified framework for defining and fitting stochastic, discrete‐time, discrete‐stage population dynamics models. The biological system is described by a state‐space model, where the true but unknown state of the population is modelled by a state process, and this is linked to survey data by an observation process. All sources of uncertainty in the inputs, including uncertainty about model specification, are readily incorporated. The paper shows how the state process can be represented as a generalization of the standard Leslie or Lefkovitch matrix. By dividing the state process into subprocesses, complex models can be constructed from manageable building blocks. The paper illustrates the approach with a model of the British grey seal metapopulation, using sequential importance sampling with kernel smoothing to fit the model.