50 resultados para stratified random sampling

em Deakin Research Online - Australia


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Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, ‘hidden’ trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

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Demographic characteristics associated with gambling participation and problem gambling severity were investigated in a stratified random survey in Tasmania, Australia. Computer-assisted telephone interviews were conducted in March 2011 resulting in a representative sample of 4,303 Tasmanian residents aged 18 years or older. Overall, 64.8 % of Tasmanian adults reported participating in some form of gambling in the previous 12 months. The most common forms of gambling were lotteries (46.5 %), keno (24.3 %), instant scratch tickets (24.3 %), and electronic gaming machines (20.5 %). Gambling severity rates were estimated at non-gambling (34.8 %), non-problem gambling (57.4 %), low risk gambling (5.3 %), moderate risk (1.8 %), and problem gambling (.7 %). Compared to Tasmanian gamblers as a whole significantly higher annual participation rates were reported by couples with no children, those in full time paid employment, and people who did not complete secondary school. Compared to Tasmanian gamblers as a whole significantly higher gambling frequencies were reported by males, people aged 65 or older, and people who were on pensions or were unable to work. Compared to Tasmanian gamblers as a whole significantly higher gambling expenditure was reported by males. The highest average expenditure was for horse and greyhound racing ($AUD 1,556), double the next highest gambling activity electronic gaming machines ($AUD 767). Compared to Tasmanian gamblers as a whole problem gamblers were significantly younger, in paid employment, reported lower incomes, and were born in Australia. Although gambling participation rates appear to be falling, problem gambling severity rates remain stable. These changes appear to reflect a maturing gambling market and the need for population specific harm minimisation strategies. © 2014 Springer Science+Business Media New York.

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BACKGROUND: Despite emerging evidence regarding clinical deterioration in emergency department (ED) patients, the widespread uptake of rapid response systems (RRS) in EDs has been limited. AIMS: To evaluate the effect of an ED RRS on reporting of clinical deterioration and determine if there were differences between patients who did, and did not, deteriorate during ED care. METHODS: A retrospective cross sectional design was used to conduct this single site study in Melbourne, Australia. Stratified random sampling identified 50 patients with shortness of breath, chest pain or abdominal pain per each year studied (2009-2012) giving a total of 600 patients. The intervention was an ED RRS implemented in stages. RESULTS: The frequency of clinical deterioration was 14.8% (318 episodes/89 patients). Unreported deterioration decreased each year (86.7%; 68.8%; 55.3%; 54.0%, p=0.141). Patients who deteriorated during ED care had a longer median ED length of stay (2.8h; p<0.001), were 31.9% more likely to need hospital admission (p<0.001) and 4.9% more likely to die in hospital (p=0.044). CONCLUSIONS: A staged ED specific RRS decreased the frequency of unreported clinical deterioration. Controlled multi-site studies of ED specific RRSs are needed to examine the effect of formal ED RRSs on patient outcomes.

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The Rosebank Business Precinct is one of Auckland s most highly developed Business Improvement Districts. This descriptive study, undertaken for Auckland City Council, examines the gaps between what Rosebank businesses actually want and what the workforce presently provides. A further aim was to investigate the potential for employee training, education and development in Rosebank. We conducted face-to-face interviews with about one-fifth of Rosebank companies using a 36-question questionnaire and employing random stratified cluster sampling. Fifteen of these firms also had in-depth interviews. From the present analysis, it is apparent that many firms lack leadership, leadership styles, managerial, computing and technology skills, which in turn leads to lower survival rates. Local authorities have a role to play in ontologies and epistemologies of leadership in the local organisations surveyed in Rosebank. Many owner/managers, regarded as leaders, held unsupportive attitudes toward training and education. The paper makes recommendations in the fields of labour force training, education and development; recruitment; and where leaders can recruit the right people.

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This article focuses on the background of the 'conventional' or 'old' way of recruiting, it reviews different 'new' ways; e-recruiting and its effectiveness; advantages such as accessibility and disadvantages such as transgression of some legislation in e-recruiting and the impact it has on management. Face-to-face interviews were conducted with 102 companies within that population. A 36- question questionnaire was used and we employed random stratified cluster sampling. Research done in Auckland's Rosebank Business Precinct (New Zealand) revealed that for certain job categories e-recruitment is effective. E-recruitment is revolutionising the way employers hire employees. Some implications for managers are pointed out such as the need to be trained for these changes; it can save a lot of money on advertisements; the savings could be used to develop careers or training for employees. The recommendations suggest that the HR objectives have to align with the organisational objectives to ensure that they recruit, select and employ the right candidate for the right job. A flow diagram for e-recruiting was developed by the authors for use by employers.

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Regular monitoring of seabird populations is necessary to improve our understanding of their responses to environmental change and inform conservation management. However, given the difficulty in accessing remote breeding sites and the limited resources typically available to land managers, conducting regular, extensive surveys of seabird populations is often not feasible. Our objective was to determine the minimum survey effort required to obtain accurate and precise population estimates of Short-tailed Shearwaters (Ardenna tenuirostris) and Little Penguins (Eudyptula minor), two abundant burrowing seabird species in southeastern Australia, by comparing bootstrapped means and confidence intervals under different sampling regimes on four islands. We found that, in many cases, survey effort (the proportion of transects and quadrats along transects surveyed) could be reduced. For Short-tailed Shearwaters, reducing the number of transects resulted in a maximum difference of 15% between the means at full survey effort and two levels of reduced survey effort. Means differed by <3% when we halved the number of quadrats. For Little Penguins, reducing the number of transects and quadrats by 50% resulted in differences of 7-40% and 4-34%, respectively, between the full and reduced survey effort means. Confidence intervals generally increased with decreasing survey effort for both species. Differences in required survey effort between the two species in our study may have been due to differences in burrow distribution on islands, with Short-tailed Shearwater burrows generally uniformly distributed on each island and Little Penguin burrows typically occurring in patches. These would be influenced by island-specific characteristics in concert with habitat preferences, population size, and seasonal variation in seabird abundance. Stratified sampling did not increase survey accuracy and simulations showed that large reductions in survey effort could be made under a pseudo-random sampling regime, with mean abundance estimates similar at most levels of survey effort. For both species, reducing the proportion of pseudo-random quadrats to 50% and 25% of the full survey effort produced confidence intervals of 12% and 21%, respectively, of the maximum, whereas a survey effort of 10% produced confidence intervals of up to 36% of the maximum for both species. A pseudo-random sampling regime would maximize survey efficiency because considerably fewer quadrats would be required and allow development of more efficient sampling protocols and regimes.

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Background
There is broad consensus that diets high in salt are bad for health and that reducing salt intake is a cost-effective strategy for preventing chronic diseases. The World Health Organization has been supporting the development of salt reduction strategies in the Pacific Islands where salt intakes are thought to be high. However, there are no accurate measures of salt intake in these countries. The aims of this project are to establish baseline levels of salt intake in two Pacific Island countries, implement multi-pronged, cross-sectoral salt reduction programs in both, and determine the effects and cost-effectiveness of the intervention strategies.

Methods/Design
Intervention effectiveness will be assessed from cross-sectional surveys before and after population-based salt reduction interventions in Fiji and Samoa. Baseline surveys began in July 2012 and follow-up surveys will be completed by July 2015 after a 2-year intervention period.

A three-stage stratified cluster random sampling strategy will be used for the population surveys, building on existing government surveys in each country. Data on salt intake, salt levels in foods and sources of dietary salt measured at baseline will be combined with an in-depth qualitative analysis of stakeholder views to develop and implement targeted interventions to reduce salt intake.

Discussion
Salt reduction is a global priority and all Member States of the World Health Organization have agreed on a target to reduce salt intake by 30% by 2025, as part of the global action plan to reduce the burden of non-communicable diseases. The study described by this protocol will be the first to provide a robust assessment of salt intake and the impact of salt reduction interventions in the Pacific Islands. As such, it will inform the development of strategies for other Pacific Island countries and comparable low and middle-income settings around the world.

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A method is described for making rapid in situ field measurements of riverbed topography over spatial scales of ≅1–10 m. This method uses rolling balls to make quick, accurate measurements of river-bed roughness at several spatial scales. Random sampling and replication generate multiple estimates of the fractal dimension (d) that can be used to test for significant differences in the complexity of riverbed architecture between habitat types and spatial scales.

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Our aim was to provide a description of the self-reported health beliefs of a sample of Victorian public housing tenants, and to identify how gender, age and geographic location relate to these beliefs. Telephone interviews were conducted with a stratified random sample of 360 tenants, asking questions such as what they believe are the major health problems for men and women, what they do to keep healthy, and what makes it difficult to keep healthy. There were many differences in the beliefs held by older participants compared with those of younger participants. By asking about health in general, rather than specific aspects of health, this research identified the views about health which are most salient to participants, rather than those prompted by a survey on a particular disease or health behaviour. The health promotion implications of these findings are discussed.

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Introduction: There is wide variation in emergency nursing practice in terms of initial patient assessment and the interventions implemented in response to these patient assessment findings. It is hypothesised that written ED nursing practice standards will reduce variability in documentation standards related to initial patient assessment.

Aim: This study aimed to examine the effect of written ED nursing practice standards augmented by an in-service education programme on the documentation of the initial nursing assessment.

Method: A pre-test/post-test design was used. Initial patient assessment was assessed using the Emergency Department Observation Chart. All adult patients (>18 years) who presented with chest pain and who were triaged to the general adult cubicles were eligible for inclusion in the study. Random sampling was used to select the patients for the pre-test (n = 78) and post-test groups (n = 74).

Results: There was significant improvement in documentation of all aspects of symptom assessment except quality and historical variables: pre-hospital care, cardiac risk factors, and past medical history. Improvements in documentation of elements of primary survey assessment were variable. There were significant increases in documentation of respiratory effort, chest auscultation findings, capillary refill and conscious state. There was a significant 18.3% decrease in the frequency of documentation of respiratory rate and no significant changes in documentation of oxygen saturation, heart rate or blood pressure.

Conclusion: Written ED nursing practice standards were effective in improving the documentation of some elements of initial nursing assessment for patients with chest pain. Active implementation strategies are important to ensure effective uptake of written practice standards and the relationship between nursing documentation and actual clinical practice warrants further consideration using a naturalistic approach in real practice settings.

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This study aimed to describe the characteristics of the elderly population living alone, and to examine how living alone relates to feeling lonely. Interviews were conducted with a stratified random sample of 4,859 elderly individuals living in Kaohsiung, Taiwan. Variables collected included demographic information, living alone or not, activities of daily living
(ADL), instrumental activities of daily living (IADL), Short Portable Mental Status Questionnaire (SPMSQ), chronic conditions, perceived social support, and a subjective measure of feeling lonely. Using logistic regression, it was found that factors associated with living alone included gender, marital status, occupation, source of income, religion, and IADL. Living alone was, in tum, related to decreased levels of both perceived social support
and feeling lonely after adjustment for potential confounders. Managing retired life is important for adult elders, particularly for men. Lack ofsocial support is common among the elderly community who live alone, which could wel1 be a main reason for this group to feel lonely. As loneliness is linked to physical and mental health problems, increasing social support and facilitating friendship should be factored into life-style management for
communities of elderly.

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Background: Fine motor difficulties can impact on the academic, social and emotional development of a student. Aim: The aims of this paper are to: (i) investigate the need for support to students experiencing fine motor  difficulties from the perspective of their classroom teachers, and (ii) report on the level of knowledge teachers have in regard to the role of occupational therapists in supporting students with fine motor difficulties.  Methods: Fifteen teachers from a stratified random sample of public schools within two regions of Victoria, Australia, were interviewed in this qualitative, grounded theory investigation. Results: Results showed that the current level of support for students with fine motor difficulties is inadequate. Conclusion: Occupational therapists in Victoria need to advocate their role in developing the fine motor skills of students at both an organisational and an individual level in order to increase the access of students with fine motor difficulties to occupational therapy services.

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OBJECTIVE: To measure the prevalence of overweight, obesity and the metabolic syndrome (MetS) in rural Australia.

DESIGN, SETTING AND PARTICIPANTS: Cross-sectional surveys were conducted in two rural areas in Victoria and South Australia in 2004-2005. A stratified random sample of men and women aged 25-74 years was selected from the electoral roll. Data were collected by a self-administered questionnaire, physical measurements and laboratory tests.

MAIN OUTCOME MEASURES: Prevalence of overweight and obesity, as defined by body mass index (BMI) and waist circumference; prevalence of MetS and its components.

RESULTS: Data on 806 participants (383 men and 423 women) were analysed. Based on BMI, the prevalence of overweight and obesity combined was 74.1% (95% CI, 69.7%-78.5%) in men and 64.1% (95% CI, 59.5%-68.7%) in women. Based on waist circumference, the prevalence of overweight and obesity was higher in women (72.4%; 95% CI, 68.1%-76.7%) than men (61.9%; 95% CI, 57.0%-66.8%). The overall prevalence of obesity was 30.0% (95% CI, 26.8%-33.2%) based on BMI (> or = 30.0 kg/m(2)) and 44.7% (95% CI, 41.2%-48.1%) based on waist circumference (> or = 102 cm [men] and > or= 88 cm [women]). The prevalence of MetS as defined by the US National Cholesterol Education Program Adult Treatment Panel III 2005 criteria was 27.1% (95% CI, 22.7%-31.6%) in men and 28.3% (95% CI, 24.0%-32.6%) in women; based on International Diabetes Federation criteria, prevalences for men and women were 33.7% (95% CI, 29.0%-38.5%) and 30.1% (95% CI, 25.7%-34.5%), respectively. Prevalences of MetS, central (abdominal) obesity, hyperglycaemia, hypertension and hypertriglyceridaemia increased with age.

CONCLUSIONS: In rural Australia, prevalences of MetS, overweight and obesity are very high. Urgent population-wide action is required to tackle the problem.

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Childhood obesity is an increasing health problem in New Zealand and many other countries. Information is needed to guide interventions that reduce the ‘obesogenic’ (obesity-promoting) elements of school environments. The aim of this study was to identify and measure the obesogenic elements of the school environment and the canteen sales of energy-dense foods and drinks. A self-completion questionnaire was developed for assessing each school's nutrition environment and mailed to a stratified random sample of New Zealand schools. The responses from primary schools (n = 200, response rate 61%) were analysed. Only 15.5% of schools had purpose-built canteen facilities and over half ran a food service for profit (31% profit to the school, 24.5% profit for the contractors). Only 16.5% of schools had a food policy, although 91% of those rated the policy as effective or very effective. The most commonly available foods for sale were pies (79%), juice (57%) and sausage rolls (54.5%). Filled rolls were the most expensive item (mean $1.79) and fruit the least expensive (mean $0.47). The ratio of ‘less healthy’ to ‘more healthy’ main choices was 5.6:1, for snacks it was 9.3:1 and for drinks it was 1.4:1. In contrast, ~60% of respondents said that nutrition was a priority for the school. Only 50% felt there was management support for healthy food choices and only 39% agreed that mainly nutritious food was offered by the food service. ‘Less healthy’ choices dominated food sales by more than 2:1, with pies being the top selling item (>55 000 per week). We found that the food environment was not conducive to healthy food choices for the children at New Zealand schools and that this was reflected in the high sales of relatively unhealthy foods from the school food services. Programmes that improve school food through policies, availability, prices and school ethos are urgently needed.

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In order to establish what constitutes current primary practice in Victoria, video and other data were collected from a stratified random sample of ten year 3 and 4 classrooms in Victoria. Three video vignettes, representing the contrasting pedagogical flows captured on the videotapes, were produced to stimulate discussion in three separate Focus Groups of randomly selected teachers, principals, and mathematics teacher educators and consultants. This paper reports on their views of what constitutes current Victorian practice in primary mathematics