A review of two journals found that articles using multivariable logistic regression frequently did not report commonly recommended assumptions

Background and Objective: To examine if commonly recommended assumptions for multivariable logistic regression are addressed in two major epidemiological journals. Methods: Ninety-nine articles from the Journal of Clinical Epidemiology and the American Journal of Epidemiology were surveyed for 10 criteria: six dealing with computation and four with reporting multivariable logistic regression results. Results: Three of the 10 criteria were addressed in 50% or more of the articles. Statistical significance testing or confidence intervals were reported in all articles. Methods for selecting independent variables were described in 82%, and specific procedures used to generate the models were discussed in 65%. Fewer than 50% of the articles indicated if interactions were tested or met the recommended events per independent variable ratio of 10: 1. Fewer than 20% of the articles described conformity to a linear gradient, examined collinearity, reported information on validation procedures, goodness-of-fit, discrimination statistics, or provided complete information on variable coding. There was no significant difference (P >.05) in the proportion of articles meeting the criteria across the two journals. Conclusion: Articles reviewed frequently did not report commonly recommended assumptions for using multivariable logistic regression. (C) 2004 Elsevier Inc. All rights reserved.

On the estimation and comparison of short-rate models using the generalised method of moments

Subsequent to the influential paper of [Chan, K.C., Karolyi, G.A., Longstaff, F.A., Sanders, A.B., 1992. An empirical comparison of alternative models of the short-term interest rate. Journal of Finance 47, 1209-1227], the generalised method of moments (GMM) has been a popular technique for estimation and inference relating to continuous-time models of the short-term interest rate. GMM has been widely employed to estimate model parameters and to assess the goodness-of-fit of competing short-rate specifications. The current paper conducts a series of simulation experiments to document the bias and precision of GMM estimates of short-rate parameters, as well as the size and power of [Hansen, L.P., 1982. Large sample properties of generalised method of moments estimators. Econometrica 50, 1029-1054], J-test of over-identifying restrictions. While the J-test appears to have appropriate size and good power in sample sizes commonly encountered in the short-rate literature, GMM estimates of the speed of mean reversion are shown to be severely biased. Consequently, it is dangerous to draw strong conclusions about the strength of mean reversion using GMM. In contrast, the parameter capturing the levels effect, which is important in differentiating between competing short-rate specifications, is estimated with little bias. (c) 2006 Elsevier B.V. All rights reserved.

Adaptive responses of wild mungbean (Vigna radiata ssp sublobata) to photo-thermal environment. I. Phenology

The phenology of 11 diverse accessions of wild mungbean was observed under natural and artificial photoperiod - temperature conditions, in order to examine whether genotypic differences might be attributed to adaptive responses to photo-thermal conditions. There was large variation in phenological response among accessions and across environments, much of which was due to differences in the duration of the pre-flowering phase. Accessions that flowered earlier tended to flower for longer, apart from 2 earlier flowering, inland Australian lines that were also earlier maturing. The patterns of response in time from sowing to flowering over environment were consistent with quantitative short-day photoperiodic adaptation, a conclusion supported by the effects of artificial day-length extension and by 'goodness of fit' of the observed responses to standard models relating rate of development to photoperiod and temperature. The fitted models indicated that rate of development towards flowering was hastened by warmer temperatures, and delayed by longer day lengths, with differential sensitivity between accessions to both factors. The models also suggested that photoperiod was more important for accessions collected closer to the equator, which were generally later flowering as a consequence. Conversely, temperature was relatively more important in lines from higher latitudes. Modelling also suggested that the period from first flowering to maturity was sensitive to photoperiod and temperature. Again, longer days appeared to prolong growth and delay maturity. However, cooler temperatures accelerated rather than slowed maturity, by suppressing further vegetative growth. The variation observed indicated that there is considerable scope for using the wild population to broaden the adaptation of cultivated mungbean. In particular, the unusual response of a late-flowering, photoperiod-insensitive accession warrants further study to establish whether the wild population contains a unique 'long juvenile' trait analogous to that being used for improving phenological adaptation in soybean.

Cognitive fit between conceptual schemas and internal problem representations: The case of geospatio-temporal conceptual schema comprehension

Geospatio-temporal conceptual models provide a mechanism to explicitly represent geospatial and temporal aspects of applications. Such models, which focus on both what and when/where, need to be more expressive than conventional conceptual models (e.g., the ER model), which primarily focus on what is important for a given application. In this study, we view conceptual schema comprehension of geospatio-temporal data semantics in terms of matching the external problem representation (that is, the conceptual schema) to the problem-solving task (that is, syntactic and semantic comprehension tasks), an argument based on the theory of cognitive fit. Our theory suggests that an external problem representation that matches the problem solver's internal task representation will enhance performance, for example, in comprehending such schemas. To assess performance on geospatio-temporal schema comprehension tasks, we conducted a laboratory experiment using two semantically identical conceptual schemas, one of which mapped closely to the internal task representation while the other did not. As expected, we found that the geospatio-temporal conceptual schema that corresponded to the internal representation of the task enhanced the accuracy of schema comprehension; comprehension time was equivalent for both. Cognitive fit between the internal representation of the task and conceptual schemas with geospatio-temporal annotations was, therefore, manifested in accuracy of schema comprehension and not in time for problem solution. Our findings suggest that the annotated schemas facilitate understanding of data semantics represented on the schema.

Factor structure of the Mood and Anxiety Symptom Questionnaire does not generalize to an anxious/depressed sample

Objective: The tripartite model of anxiety and depression has been proposed as a representation of the structure of anxiety and depression symptoms. The Mood and Anxiety Symptom Questionnaire (MASQ) has been put forwards as a valid measure of the tripartite model of anxiety and depression symptoms. This research set out to examine the factor structure of anxiety and depression symptoms in a clinical sample to assess the MASQ's validity for use in this population. MethodsThe present study uses confirmatory factor analytic methods to examine the psychometric properties of the MASQ in 470 outpatients with anxiety and mood disorder. Results: The results showed that none of the previously reported two-factor, three-factor or five-factor models adequately fit the data, irrespective of whether items or subscales were used as the unit of analysis. Conclusions: It was concluded that the factor structure of the MASQ in a mixed anxiety/depression clinical sample does not support a structure consistent with the tripartite model. This suggests that researchers using the MASQ with anxious/depressed individuals should be mindful of the instrument's psychometric limitations.

Fracture load and marginal fit of shrinkage-free ZrSiO4 all-ceramic crowns after chewing simulation

The aim of this in vitro study was to evaluate the fracture load and marginal accuracy of crowns made from a shrinkage-free ZrSiO4 ceramic cemented with glass-ionomer or composite cement after chewing simulation. Thirty-two human mandibular molars were randomly divided into two groups. All teeth were prepared for and restored with shrinkage-free ZrSiO4 ceramic crowns (Everest HPC (R), KaVo). The crowns of group A (N = 16) were luted to the teeth using KetacCem (R) and group B (N = 16) were adhesively cemented using Panavia (R) 21EX. Measurements of the marginal accuracy before and after cementation were made using replicas and an image analysis system. All specimens were exposed to 1.2 million cycles of thermo-mechanical fatigue in a chewing simulator. Surviving specimens were subsequently loaded until fracture in a static testing device. Fracture loads (N) were recorded. All specimens survived chewing simulation. The mean fracture loads (+/- s.d.) were Group A, 1622 N (+/- 433); group B, 1957 N (+/- 806). There was no significant difference between the two groups (P > 0.05). The marginal gap values before cementation were (mean +/- s.d.): Group A, 32.7 mu m (+/- 6.8); group B, 33.0 mu m (+/- 6.7).The mean marginal gap values after cementation were (+/- s.d.): Group A, 44.6 mu m (+/- 6.7); group B, 46.6 mu m (+/- 7.7). The marginal openings were significantly higher after cementation for both groups (P < 0.05). All test groups demonstrated fracture load and marginal accuracy values within the range of clinical acceptability.

Passion and psychological adjustment: A test of the person-environment fit hypothesis

Passion represents a strong inclination toward an activity that is important, liked, and in which significant time is invested. Although a harmonious passion is well integrated in one’s identity and is emitted willingly, obsessive passion is not well integrated and is emitted out of internal pressure. This study tested for the presence of a Passion × Environment fit interaction with respect to psychological adjustment. Elite hockey players (N = 233) who tried out for a team in a highly competitive league participated in this short-term longitudinal study. As hypothesized, being selected by the highly competitive leagues led to higher psychological adjustment than not being selected by such leagues. Two months later, an interaction revealed that among athletes who were playing in highly competitive leagues, obsessively passionate athletes reported higher psychological adjustment than did harmonious athletes. Conversely, among athletes playing in less competitive leagues, harmonious athletes reported higher psychological adjustment than did obsessive athletes.

Being fit and looking healthy: Young women's and men's constructions of health and fitness

We drew on Foucault's notion of 'practices of the self' to examine how young people take up, negotiate, and resist the imperatives of a public health discourse concerned with the relationships between health, fitness, and the body. We did this through a discussion of the ways young women and men talk about their own and others' bodies, in the context of a number of in-depth interviews conducted for the Life Activity Project, a study of the place and meaning of physical activity in young people's lives, funded by an Australian Research Council Grant. We found that the young women and men in the study engaged the health/fitness discourse very differently: for the young men, health conflated with fitness as an embodied capacity to do physical work; and for the young women, health was a much more difficult and complex project associated with managing and monitoring practices associated with eating and exercise to maintain an 'appropriate' body shape.

Where Do Flappers Fit In?: The Photography of Modern Fashion in Australia

The visual technique of fashion photography is examined which taught Australian women to look modern. Especially fashion photography intervenes ambivalently into the story of Australian modernism and modernity. During 1920s and 1930s within the fashion press there were synergies and differences between commercial fashion photography, celebrity and cinematic portraiture, and social set endorsement. However, modernism was widely acknowledged in Australia during the 1920s through women's spaces, their fashions and culture of department stores.

Fighting fit: thermal plasticity of metabolic function and fighting success in the crayfish Cherax destructor

1. We examined the effect of thermal acclimation on fighting success and underlying performance traits in the crayfish Cherax destructor. We tested the hypothesis that animals will be more successful when fighting at their acclimation temperature than at a colder or warmer temperature, and that changes in metabolic capacity underlie differences in behavioural performance. 2. Thermal acclimation (to 20 degrees C and to 30 degrees C) had a significant effect on behavioural contests, and the likelihood of winning was significantly greater when individuals fought at their acclimation temperature against an individual from an alternate acclimation temperature. 3. The ratio of ADP stimulated respiration to proton leak (respiratory control ratio) of isolated mitochondria increased significantly in chelae muscle of the cold-acclimated group, and differences in respiratory control ratio between winners and losers were significantly correlated with the outcome of agonistic encounters. However, acclimation did not affect tall muscle mitochondria or the activity of pyruvate kinase in either chelae or tail muscle. 4. The force produced by closing chelae was thermally insensitive within acclimation groups, and there were no significant differences between acclimation treatments. None the less, differences in chelae width between contestants were significantly correlated with the outcome of agonistic encounters, but this perceived resource holding power did not reflect the actual power of force production. 5. Thermal acclimation in C destructor has beneficial consequences for dominance and competitive ability, and the success of cold acclimated animals at the cold temperatures can be at least partly explained by concomitant up-regulation of oxidative ATP production capacity.

Predictors of emotional well-being following a 'false positive' breast cancer screening result

Using a short-term longitudinal design, and consistent with a stress and coping perspective, this study examined the main and stress-buffering effects of social support and coping on emotional well-being following a 'false positive' breast cancer screening result. Immediately prior to obtaining results of follow-up assessment, 178 women completed measures of emotional well-being, stress appraisal, coping strategies and social support. Six weeks later, 85 women found to be cancer free completed a measure of well-being. Hierarchical regression analyses were used to examine the effects of social support and coping on well-being after controlling for initial well-being and stress appraisal. Consistent with predictions, avoidant coping was associated with higher levels of emotional well-being and social support was found to have a stress buffering effect on well-being. Active-cognitive coping strategies had a stress-buffering effect on well-being. Findings suggest that social support and coping do influence emotional well-being following recall for follow-up assessment of a 'false positive' breast cancer screening result.