70 resultados para weak informative prior

em Deakin Research Online - Australia


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1. Informative Bayesian priors can improve the precision of estimates in ecological studies or estimate parameters for which little or no information is available. While Bayesian analyses are becoming more popular in ecology, the use of strongly informative priors remains rare, perhaps because examples of informative priors are not readily available in the published literature.
2. Dispersal distance is an important ecological parameter, but is difficult to measure and estimates are scarce. General models that provide informative prior estimates of dispersal distances will therefore be valuable.
3. Using a world-wide data set on birds, we develop a predictive model of median natal dispersal distance that includes body mass, wingspan, sex and feeding guild. This model predicts median dispersal distance well when using the fitted data and an independent test data set, explaining up to 53% of the variation.
4. Using this model, we predict a priori estimates of median dispersal distance for 57 woodland-dependent bird species in northern Victoria, Australia. These estimates are then used to investigate the relationship between dispersal ability and vulnerability to landscape-scale changes in habitat cover and fragmentation.
5. We find evidence that woodland bird species with poor predicted dispersal ability are more vulnerable to habitat fragmentation than those species with longer predicted dispersal distances, thus improving the understanding of this important phenomenon.
6. The value of constructing informative priors from existing information is also demonstrated. When used as informative priors for four example species, predicted dispersal distances reduced the 95% credible intervals of posterior estimates of dispersal distance by 8-19%. Further, should we have wished to collect information on avian dispersal distances and relate it to species' responses to habitat loss and fragmentation, data from 221 individuals across 57 species would have been required to obtain estimates with the same precision as those provided by the general model.

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1. Informative Bayesian priors can improve the precision of estimates in ecological studies or estimate parameters for which little or no information is available. While Bayesian analyses are becoming more popular in ecology, the use of strongly informative priors remains rare, perhaps because examples of informative priors are not readily available in the published literature.

2. Dispersal distance is an important ecological parameter, but is difficult to measure and estimates are scarce. General models that provide informative prior estimates of dispersal distances will therefore be valuable.

3. Using a world-wide data set on birds, we develop a predictive model of median natal dispersal distance that includes body mass, wingspan, sex and feeding guild. This model predicts median dispersal distance well when using the fitted data and an independent test data set, explaining up to 53% of the variation.

4. Using this model, we predict a priori estimates of median dispersal distance for 57 woodland-dependent bird species in northern Victoria, Australia. These estimates are then used to investigate the relationship between dispersal ability and vulnerability to landscape-scale changes in habitat cover and fragmentation.

5. We find evidence that woodland bird species with poor predicted dispersal ability are more vulnerable to habitat fragmentation than those species with longer predicted dispersal distances, thus improving the understanding of this important phenomenon.

6. The value of constructing informative priors from existing information is also demonstrated. When used as informative priors for four example species, predicted dispersal distances reduced the 95% credible intervals of posterior estimates of dispersal distance by 8-19%. Further, should we have wished to collect information on avian dispersal distances and relate it to species' responses to habitat loss and fragmentation, data from 221 individuals across 57 species would have been required to obtain estimates with the same precision as those provided by the general model.

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Telemedicine emerges as a viable solution to New Zealand health providers in reaching out to rural patients, in offering medical services and conducting administrative meetings and training. No research exists about adoption of telemedicine in New Zealand. The purpose of this case study was to explain factors influencing adoption of telemedicine utilizing video conferencing technology (TMVC) within a New Zealand hospital known as KiwiCare. Since TMVC is part of IT, tackling it from within technological innovation literature may assist in providing an insight into its adoption within KiwiCare and into the literature. Findings indicate weak presence of critical assessment into technological innovation factors prior to the adoption decision, thereby leading to its weak utilization. Factors like complexity, compatibility and trialability were not assessed extensively by KiwiCare and would have hindered TMVC adoption. TMVC was mainly assessed according to its relative advantage and to its cost effectiveness along with other facilitating and accelerating factors. This is essential but should be alongside technological and other influencing factors highlighted in the literature.

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Several studies have demonstrated that oral glucose tolerance is impaired in the immediate postexercise period. A double-tracer technique was used to examine glucose kinetics during a 2-h oral glucose (75 g) tolerance test (OGTT) 30 min after exercise (Ex, 55 min at 71 ± 2% of peak O2 uptake) and 24 h after exercise (Rest) in endurance-trained men. The area under the plasma glucose curve was 71% greater in Ex than in Rest (P = 0.01). The higher glucose response occurred even though whole body rate of glucose disappearance was 24% higher after exercise (P = 0.04, main effect). Whole body rate of glucose appearance was 25% higher after exercise (P = 0.03, main effect). There were no differences in total (2 h) endogenous glucose appearance (RaE) or the magnitude of suppression of RaE, although RaE was higher from 15 to 30 min during the OGTT in Ex. However, the cumulative appearance of oral glucose was 30% higher in Ex (P = 0.03, main effect). There were no differences in glucose clearance rate or plasma insulin responses between the two conditions. These results suggest that adaptations in splanchnic tissues by prior exercise facilitate greater glucose output from the splanchnic region after glucose ingestion, resulting in a greater glycemic response and, consequently, a greater rate of whole body glucose uptake.

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Against a background of 'second-wave' lifelong learning in Aotearoa New Zealand a new framework for post-compulsory national qualifications was introduced. The resulting competency-based system was argued to present a number of benefits for mature women including flexibility in curriculum and delivery and portability across educational sectors. Competency-based education was to include provision for recognition of prior skills and knowledge gained in formal learning environments and the workplace as well as informal learning environments such as the home and the community. Such recognition was a significant factor in gaining support from women’s groups given the potential to recognize and value the domestic labour of women and the skills and knowledge that flow from it. This article explores the rhetoric around recognition of prior learning and discusses approaches to realise its potential. It then draws on research undertaken in Aotearoa New Zealand to suggest that the potential of recognition of prior learning is yet to be realised.

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This study examined the effect of vegetarianism on skeletal muscle total creatine (TCr) content and creatine transporter (CreaT) gene expression, prior to and during 5 d of Cr supplementation (CrS). In a double-blind, crossover design, 7 vegetarians (VEG) and nonvegetarians (NVEG) were assigned Cr or placebo supplements for 5 d and after 5 wk, received the alternative treatment. Muscle sampling occurred before, and after 1 and 5 d of treatment ingestion. Basal muscle TCr content was lower (P < 0.05) in VEG compared with NVEG. Muscle TCr increased (P < 0.05) throughout the Cr trial in both groups but was greater (P < 0.05) in VEG compared with NVEG, at days 1 and 5. CreaT gene expression was not different between VEG and NVEG. The results indicate that VEG have a lower muscle TCr content and an increased capacity to load Cr into muscle following CrS. Muscle CreaT gene expression does not appear to be affected by vegetarianism.

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Using a theoretical framework extracted from thetechnological innovation theories, this research attempts to explain factors influencing the adoption and diffusion of telemedicine utilising the video conferencing technology (TMVC) for dermatology within health Waikato (HW) in New Zealand. Findings indicate weak presence of critical assessment into technological innovation factors prior to TMVC adoption. Factors such as complexity, compatibility, and trialability were not assessed extensively by HW and could have hindered its adoption. TMVC was mainly assessed according to its relative advantage and cost effectiveness. This is essential but should consider other important factors explained in this research. The successful diffusion of TMVC in the case study relied on its economical benefit and on its effectiveness as a diagnostic tool. This research highlights the importance of the product champion factor on the successful adoption and diffusion of TMVC.

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We analyze a principal-agent model with moral hazard in which the principal has private information about the technology. We characterize Perfect Bayesian Equilibria of the contracting game that possess the following properties: (i) a principal with a more informative technology ends up earning less profits than a principal with a less informative one does; (ii) compared to the complete information case, the actions implemented by the privately informed principal can be distorted; (iii) the agent can end up being better off when the principal has private information.

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The current study addressed how the timing of interviews affected children's memories of unique and repeated events. Five- to six-year-olds (N= 125) participated in activities 1 or 4 times and were misinformed either 3 or 21 days after the only or last event. Although single-experience children were subsequently less accurate in the 21- versus 3-day condition, the timing of the misinformation session did not affect memories of repeated-experience children regarding invariant details. Children were more suggestible in the 21- versus 3-day condition for variable details when the test occurred soon after misinformation presentation. Thus, timing differentially affected memories of single and repeated events and depended on the combination of event-misinformation and misinformation-test delays rather than the overall retention interval.

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In Australia, financial literacy is not given prominence within the education system, and it is a general view that financial literacy is gained through ‘hands on’ experience in earning and spending money; further, financial education seems to occur only when people take a loan or experience financial difficulties (Hajaj, 2002). This is not sufficient if people need to make informed decisions about their investments and, because of a number of social factors, it has become necessary to educate the majority of the adult population in Australia in Financial Literacy over a relatively short period of time. Given the large numbers requiring such an education, the seminar approach is being widely used, however is it effective? Drawing on the adult education literature, this study examined the effectiveness of the seminar approach by surveying adult participants in a Financial Literacy seminar. The survey found that while a majority of participants (50%) expressed none or weak financial knowledge prior to attending the seminar and 45% expressed that they only had a moderate rate of financial knowledge, a majority of 63% strongly agreed or agreed to the seminar improving their knowledge of the need for retirement savings. Furthermore, 58% of participants were either confident or very confident of being able to apply what they learned in the seminar to achieving their retirement savings goal. These findings suggest that the seminar approach was effective in educating adults and improved their level of financial literacy. Future research could investigate whether the level of financial knowledge gained during the seminar is retained over a considerable period of time.

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One of the key applications of microarray studies is to select and classify gene expression profiles of cancer and normal subjects. In this study, two hybrid approaches–genetic algorithm with decision tree (GADT) and genetic algorithm with neural network (GANN)–are utilized to select optimal gene sets which contribute to the highest classification accuracy. Two benchmark microarray datasets were tested, and the most significant disease related genes have been identified. Furthermore, the selected gene sets achieved comparably high sample classification accuracy (96.79% and 94.92% in colon cancer dataset, 98.67% and 98.05% in leukemia dataset) compared with those obtained by mRMR algorithm. The study results indicate that these two hybrid methods are able to select disease related genes and improve classification accuracy.

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There has never been, and will never be, a randomized double-blind placebo-controlled trial demonstrating that exercise in youth, adulthood or old age reduces fragility or osteoporosis-related fractures in old age. The next level of evidence, a randomized, controlled but unblinded study with fractures as an end-point is feasible but has never been done. The basis for the belief that exercise reduces fractures is derived from lower levels of ‘evidence’, namely, retrospective and prospective observation cohort studies and case–control studies. These studies are at best hypothesis generating, never hypothesis testing. They are all subject to many systematic biases and should be interpreted with extreme scepticism. Surrogate measures of anti-fracture efficacy are the next level of evidence, such as the demonstration of a reduction in risk factors for falls, a reduction in falls, a reduction in fractures due to falls, an increase in peak bone size and mass, prevention of bone loss in midlife and restoration of bone mass and structure in old age.