21 resultados para multivariate analysis of covariance

em Deakin Research Online - Australia


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This study examines how survey design characteristics impact on participant satisfaction, future intentions to complete surveys, and intention to recommend the survey to others, based on panel members, extracted from three different panels, who randomly received one out of eight developed surveys, varying length, involvement and interactivity. The experiment was designed for an Australian industry client. The multivariate analysis of covariance (MANCOVA hereafter) results suggest that there are differences based on the panels used, and longer surveys are viewed more positively. Interaction occurs between panels and involvement, but other two way interaction effects are insignificant. Implications for survey design and future research are discussed.

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Recently effective connectivity studies have gained significant attention among the neuroscience community as Electroencephalography (EEG) data with a high time resolution can give us a wider understanding of the information flow within the brain. Among other tools used in effective connectivity analysis Granger Causality (GC) has found a prominent place. The GC analysis, based on strictly causal multivariate autoregressive (MVAR) models does not account for the instantaneous interactions among the sources. If instantaneous interactions are present, GC based on strictly causal MVAR will lead to erroneous conclusions on the underlying information flow. Thus, the work presented in this paper applies an extended MVAR (eMVAR) model that accounts for the zero lag interactions. We propose a constrained adaptive Kalman filter (CAKF) approach for the eMVAR model identification and demonstrate that this approach performs better than the short time windowing-based adaptive estimation when applied to information flow analysis.

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Event related potential (ERP) analysis is one of the most widely used methods in cognitive neuroscience research to study the physiological correlates of sensory, perceptual and cognitive activity associated with processing information. To this end information flow or dynamic effective connectivity analysis is a vital technique to understand the higher cognitive processing under different events. In this paper we present a Granger causality (GC)-based connectivity estimation applied to ERP data analysis. In contrast to the generally used strictly causal multivariate autoregressive model, we use an extended multivariate autoregressive model (eMVAR) which also accounts for any instantaneous interaction among variables under consideration. The experimental data used in the paper is based on a single subject data set for erroneous button press response from a two-back with feedback continuous performance task (CPT). In order to demonstrate the feasibility of application of eMVAR models in source space connectivity studies, we use cortical source time series data estimated using blind source separation or independent component analysis (ICA) for this data set.

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This paper provides a fonnal ranking of the popularity of financial ratios in modeling corporate collapse. The analysis identified 48 financial ratios and ranked them according to their usefulness as portrayed in 53 studies that have utilized such ratios in modeling corporate collapse. The methodologies adopted in those studies are predominantly of the "multivariate" type. The 53 studies extend from 1966 to 2002, inclusive.

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In Australia, male sports attendees outnumber female sports attendees by 25%, yet little research has been conducted into the attendance motives of women. This study undertakes an analysis of 460 respondents using descriptive and multivariate statistics to distinguish the attendance motivations of women and compare them directly to those of male attendees. The findings suggest that female attendance can be influenced through management and promotional strategies.

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The inherent variability in incoming material and process conditions in sheet metal forming makes quality control and the maintenance of consistency extremely difficult. A single FEM simulation is successful at predicting the formability for a given system, however lacks the ability to capture the variability in an actual production process due to the numerical deterministic nature. This paper investigates a probabilistic analytical model where the variation of five input parameters and their relationship to the sensitivity of springback in a stamping process is examined. A range of sheet tensions are investigated, simulating different operating windows in an attempt to highlight robust regions where the distribution of springback is small. A series of FEM simulations were also performed, to compare with the findings from the analytical model using AutoForm Sigma v4.04 and to validate the analytical model assumptions.

Results show that an increase in sheet tension not only decreases springback, but more importantly reduces the sensitivity of the process to variation. A relative sensitivity analysis has been performed where the most influential parameters and the changes in sensitivity at various sheet tensions have been investigated. Variation in the material parameters, yield stress and n-value were the most influential causes of springback variation, when compared to process input parameters such as friction, which had a small effect. The probabilistic model presented allows manufacturers to develop a more comprehensive assessment of the success of their forming processes by capturing the effects of inherent variation.

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A wine fermentation has been monitored on a daily basis by 1H NMR spectroscopy. Following data pre-processing that includes synthesis of the spectra to ensure all peaks are of constant half-width, the series of spectra were examined using generalised two-dimensional correlation techniques. Synchronous and asynchronous data maps have been generated and employed to interpret the changes in the fermentation process as a function of time. The results illustrate the potential of high resolution NMR with multivariate data analysis as a tool for process monitoring and the manner in which two-dimensional correlation mapping can aid in data interpretation.

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Objective: To identify any association between the response priority code generated during calls to the ambulance communication centre and patient reports of pain severity.

Methods: A retrospective analysis of patient care records was undertaken for all patients transported by paramedics over a 7-day period. The primary research interest was the association between the response code allocated at the time of telephone triage and the initial pain severity score recorded using a numeric rating scale (NRS). Univariate and multivariate logistic regression methods were used to analyse the association between the response priority variable and explanatory variables.

Results: There were 1246 cases in which both an initial pain score using the NRS and a response code were recorded. Of these cases, 716/1246 (57.5%) were associated with a code 1 ("time-critical") response. After adjusting for gender, age, cause of pain and duration of pain, a multivariate logistic regression analysis found no significant change in the odds of a patient in pain receiving a time-critical response compared with patients who had no pain, regardless of their initial pain score (NRS 1–3, odds ratio (OR) 1.11, 95% CI 0.7 to 1.8; NRS 4–7, OR 1.12, 95% CI 0.7 to 1.8; NRS 8–10, OR 0.84, 95% CI 0.5 to 1.4).

Conclusion: The severity of pain experienced by the patient appeared to have no influence on the priority (urgency) of the dispatch response. Triage systems used to prioritise ambulance calls and decide the urgency of response or type of referral options should consider pain severity to facilitate timely and humane care.

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Background The aim of this study was to identify specific bone characteristics of stress fracture (SF) cases in sportswomen. To date, no tool is able to distinguish individuals who are at risk, limiting preventive measures.

Material and methods We investigated the skeletal system of sportswomen who did sustain SF in the past (n = 19) and compared it with that of female controls (C) with a similar sporting history but without any fracture history (n = 20).

Bone mass and body composition were measured using dual-energy X-ray absorptiometry. Bone micro-architecture was investigated by calcaneal ultrasound and fractal analysis of calcaneus radiographic images. Oestradiol levels were measured by E.I.A, and IGF-1 by R.I.A. Menstrual characteristics, nutrient intake, and training were assessed using questionnaires.

Results The result of the fractal analysis, expressed by the Hmean parameter, was significantly lower in the SF group, reflecting a more complex structure of the trabecular micro-architectural organization (P < 0·005). Body mass index (BMI) at birth was also found to be lower in the SF cases as compared with their C (P < 0·03).

Multivariate analysis revealed that the fractal parameter Hmean, bone mineral content (BMC) at Ward's triangle and the BMI at birth correctly assigned 84·85% of the female athletes into their respective SF or C groups (P = 0·001).

Conclusion These results suggest that the fractal parameter and the BMI at birth may be able to identify female athletes most at risk for this overuse bone injury, as their low indexes might reflect a greater skeletal sensitivity.

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Research on offending behavior rehabilitation suggests that offenders would gain the maximum benefit from programs that reflect the individual needs of different types of offender. Multivariate theories of offending behavior are thus required to inform individualized rehabilitation. The aim of the current study was to construct a multivariate model for the prolific offense of assault. Qualitative methodology was used to construct a descriptive model of assault for 25 adult assault offenders. The model incorporated the development of violent behavior, types of anger, violence motivation, and the assault offense. The model consisted of 14 categories, 10 of which allowed for individual differences in behavior. A total of 35 participant transcripts were then coded through the model where the individual differences occurred. Five main offense types were found. The characteristics of the types of assault offense gave indications for how rehabilitation may be targeted for each group.

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Background Medication side effects are an important cause of morbidity, mortality and costs in older people. The aim of our study was to examine prevalence and risk factors for self-reported medication side effects in an older cohort living independently in the community.

Methods The Melbourne Longitudinal Study on Healthy Ageing (MELSHA), collected information on those aged 65 years or older living independently in the community and commenced in 1994. Data on medication side effects was collected from the baseline cohort (n = 1000) in face-to-face baseline interviews in 1994 and analysed as cross-sectional data. Risk factors examined were: socio-demographics, health status and medical conditions; medication use and health service factors. Analysis included univariate logistic regression to estimate unadjusted risk and multivariate logistic regression analysis to assess confounding and estimate adjusted risk.

Results Self-reported medication side effects were reported by approximately 6.7% (67/1000) of the entire baseline MELSHA cohort, and by 8.5% (65/761) of those on medication. Identified risk factors were increased education level, co-morbidities and health service factors including recency of visiting the pharmacist, attending younger doctors, and their doctor's awareness of their medications. The greatest increase in risk for medication side effects was associated with liver problems and their doctor's awareness of their medications. Aging and gender were not risk factors.

Conclusion Prevalence of self-reported medication side effects was comparable with that reported in adults attending General Practices in a primary care setting in Australia. The prevalence and identified risk factors provide further insight and opportunity to develop strategies to address the problem of medication side effects in older people living independently in the community setting.

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Issue addressed: Many children consume excessive amounts of energy-dense, nutrient-poor (EDNP) or 'extra' foods and low intakes of fruit and vegetables. The aim of this study was to examine the associations between EDNP foods and ascertain whether certain EDNP foods and beverages are more likely to be eaten in association with other EDNP foods.

Methods: A cross-sectional representative population survey of children in preschool (n=764), and of school students in Years K, 2 and 4 (n=1,560) and in Years 6, 8 and 10 (n=1,685) residing in the Hunter New England region of New South Wales, Australia. Dietary data were collected using a short food frequency questionnaire. Multivariate logistic regression models examined the association between EDNP foods and fruit and vegetable intake. Data were stratified by sex and age cohort.

Results: More frequent consumption of some EDNP food types was significantly associated with more frequent consumption of other EDNP foods. Fast food and soft drinks consumption were associated with each other as well as with fried potato and salty snacks; and with lower intakes of fruit and vegetables in some but not all age groups.

Conclusion: The positive associations found between EDNP foods point towards the existence of a high-risk group of children who frequently consume a variety of EDNP foods and drinks.

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Background
Reducing patient length of stay is a high priority for health service providers. Preliminary information suggests additional Saturday rehabilitation services could reduce the time a patient stays in hospital by three days. This large trial will examine if providing additional physiotherapy and occupational therapy services on a Saturday reduces health care costs, and improves the health of hospital inpatients receiving rehabilitation compared to the usual Monday to Friday service. We will also investigate the cost effectiveness and patient outcomes of such a service.
Methods/Design A randomised controlled trial will evaluate the effect of providing additional physiotherapy and occupational therapy for rehabilitation. Seven hundred and twelve patients receiving inpatient rehabilitation at two metropolitan sites will be randomly allocated to the intervention group or control group. The control group will receive usual care physiotherapy and occupational therapy from Monday to Friday while the intervention group will receive the same amount of rehabilitation as the control group Monday to Friday plus a full physiotherapy and occupational therapy service on Saturday. The primary outcomes will be patient length of stay, quality of life (EuroQol questionnaire), the Functional Independence Measure (FIM), and health utilization and cost data. Secondary outcomes will assess clinical outcomes relevant to the goals of therapy: the 10 metre walk test, the timed up and go test, the Personal Care Participation Assessment and Resource Tool (PC PART), and the modified motor assessment scale. Blinded assessors will assess outcomes at admission and discharge, and follow up data on quality of life, function and health care costs will be collected at 6 and 12 months after discharge. Between group differences will be analysed with analysis of covariance using baseline measures as the covariate. A health economic analysis will be carried out alongside the randomised controlled trial.
Discussion This paper outlines the study protocol for the first fully powered randomised controlled trial incorporating a health economic analysis to establish if additional Saturday allied health services for rehabilitation inpatients reduces length of stay without compromising discharge outcomes. If successful, this trial will have substantial health benefits for the patients and for organizations delivering rehabilitation services.

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Effect of weighted vest suit worn during daily activities on running speed, jumping power, and agility in young men. J Strength Cond Res 26(11): 3030-3035, 2012-Previous weighted vest interventions using exercise in addition to hypergravity have been successful in improving postural balance and power production capacity. The purpose of this study was to investigate if hypergravity alone in daily activities excluding sporting activities is effective in improving neuromuscular performance in young adults. Eight male subjects (age = 32 [SD: 6] years, height = 178 [5] cm, and body mass = 81 [8] kg) wore weighted vests 3 d.wk-1 for 3 weeks during waking hours, excluding sporting activities. Control group comprised 9 male subjects (age = 32 [6] years, height = 179 [5] cm, and body mass = 83 [9] kg). Performance was assessed with countermovement jump (body mass normalized peak power), figure-of-8 running test (running time), and running velocity test at baseline and at the end of the intervention. At baseline, the groups did not differ from each other (multivariate analysis of variance [MANOVA] p = 0.828). A significant group × time interaction (MANOVA F = 5.1, p = 0.015) was observed for performance variables. Analysis of covariance indicated that the intervention improved the figureof- 8 running time (p = 0.016) (22.2 vs. 0.5%), whereas normalized peak power (0.0 vs. 1.6%) and running velocity (1.3 vs. 0.1%) were unaffected (p ≥ 0.095). Wearing weighted vests was effective in slightly improving agility-related performance in young men. Because the effect was small, applying hypergravity only during exercise probably suffices. It appears that a proper volume and intensity of hypergravity could be in the order of 5-10% body weight vest worn during up to 50% of the training sessions for a period of 3-4 weeks.