69 resultados para metaanalysis

em Deakin Research Online - Australia


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Resampling methods are used to calculate confidence limits in a metaanalysis of the association between unions and productivity for the population of U.S. studies. The available evidence points to a positive and statistically significant association between unions and productivity in the U.S. manufacturing and education sectors, of around 10% and 7%, respectively

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Because outsourcing of information systems (IS) is now widespread, it is generally assumed to be successful. It is also often assumed that outsourcing risks are easily managed. In this paper we adopt an “evidence based management” approach to first test these assumptions through a qualitative metaanalysis of academic studies into IS outsourcing outcomes. Our research reveals a shortage of reliable and valid evidence for outsourcing’s benefits, and for the level of risk involved. We then use data from a series of focus groups to explain the paradox of widespread adoption of a strategy with limited empirical support. These focus groups were interpreted through the lens of research on a
range of cognitive mechanisms and biases that are known to affect decision makers. We conclude that cognitive mechanisms that are likely to affect sourcing decisions include framing biases, cognitive dissonance, attribution error, and the “optimism”, “confirmation”, “disconfirmation” and “overconfidence” biases. Given the shortage of supporting evidence, and the potential for these biases to operate, we argue that researchers need to be more critical in their analysis of reports of the success and risks of IS outsourcing.

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The primary aim of this review was to identify and evaluate the strength of associations of the key parental factors measured in studies examining early childhood physical activity (PA). A systematic review of the literature, using databases PsychINFO, Medline, Academic Search Complete, PSYCHinfo, and CINHAL, published between January 1986 and March 2011 was conducted; 20 papers were relevant for the current review. While 12 parenting variables were identified, only 5 of these had been investigated sufficiently to provide conclusive findings. There were inconsistencies in the findings involving the social learning variable parental enjoyment and variables involving parental behaviours such as maternal depression and self-efficacy, and rules for sedentary behaviour, and parental perceptions, which included perceived importance of PA, fear of safety, and perception of child’s motor competence. Given these inconsistencies, a metaanalysis was conducted to determine whether the method of measuring PA (objective or subjective) influenced the strength of associations between the parental factors and young children’s PA. There was no difference in the strength of associations in the studies that used objective or subjective measurement (via parent self-report). Further investigation is needed to clarify and understand the specific parental influences and behaviours that are associated with PA in young children. In particular, longitudinal research is needed to better understand how parental influences and PA levels of children during the formative preschool and early elementary school years are associated.

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Despite decades of conservation efforts on the nesting beaches, the critical status of leatherback turtles shows that their survival predominantly depends on our ability to reduce at-sea mortality. Although areas where leatherbacks meet fisheries have been identified during the long distance movements between 2 consecutive nesting seasons, hot-spots of lethal interactions are still poorly defined within the nesting season, when individuals concentrate close to land. Here we report movements of satellite-tracked gravid leatherback turtles during the nesting season in Western Central Africa, South America and the Caribbean Sea, which account for about 70% of the world population. We show that during and at the end of the nesting season, leatherback turtles have the propensity to remain over the continental shelf, yet sometimes perform extended movements and may even nest in neighbouring countries. Leatherbacks exploit coastal commercial fishing grounds and face substantial accidental capture by regional coastal fisheries (e.g. at least 10% in French Guiana). This emphasises the need for regional conservation strategies to be developed at the ocean scale—both at sea and on land—to ensure the survival of the last leatherback turtles.

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This bibliography begins with this introduction followed by a general overview of meta-analysis and research synthesis methods in education. The third section cites references to illustrate how the concept of statistical integration of research findings dates back to early 20th century. Citations in the fourth section highlight early calls from educational researchers to recognize the process of synthesizing research as a scholarly endeavor in its own right. As evident from the citations in the fifth section, it was in the 1980s when monographs exclusively devoted to research synthesis methods started to be published. Since then, a number of books have been published on research synthesis methods. The sixth section cites some of the most comprehensive books on research synthesis methods and includes contributions from key players of meta-analysis current at the time. The citations in the seventh section illustrate how meta-analysis has become very popular over time. Several large organizations have been set up and software developed to support systematic reviews of research. These are cited in the eighth section. Citations in the ninth section illustrate critiques of systematic reviews. As qualitative research is becoming popular in education, sophisticated discussions of issues associated with synthesizing qualitative research have also been published, some of which are cited in the tenth section. The eleventh section presents a methodologically inclusive account of current developments in research synthesis methods. The final section cites examples of journals exclusively devoted to publishing research reviews and exemplary research synthesis with different methodologies. Individual methods of research synthesis are discussed chronologically as they became popular in educational research. Accordingly, this bibliography starts with a discussion of statistical methods of integrating research that parallels the dominance of quantitative research in education until the 1970s. As the popularity and diversity of qualitative research methods have been increasing in educational research, more methodologically inclusive discussions of research synthesis methods are becoming popular as described in the later sections of this bibliography.

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While statins target many of the pathways to neuroprogression in schizophrenia, the safety and efficacy of statins for treating schizophrenia has never been examined. This is an 8-week randomized double blind controlled clinical trial examining the efficacy and safety of adjunctive lovastatin (20 mg/day) treatment or placebo for people with schizophrenia. The baseline characteristics of the two groups were not different. Endpoint changes in Positive and Negative Syndrome Scale (PANSS) total and subscale scores did not differ between the two groups. However there was a significant difference between the doses of risperidone used in the two groups. The mean dose in the lovastatin and placebo groups were 4.8(1.8) and 3.4(1.4) mg/day, respectively (P<.03). No serious adverse events were reported. Slowness of movements, muscle rigidity, increased appetite, and decreased energy were the most common adverse effects, and these rates did not differ between the two groups. This study failed to demonstrate a benefit of lovastatin on symptoms of schizophrenia. This combination was well tolerated. However, a higher dosage of risperidone was used for treating the disorder in those taking concomitant lovastatin compared to placebo.

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Obsessive-Compulsive Disorder (OCD) is a common chronic psychiatric disorder that constitutes a leading cause of disability. Although Cognitive-Behaviour Therapy (CBT) has been shown to be an effective treatment for OCD, this specialised treatment is unavailable to many due to access issues and the social stigma associated with seeing a mental health specialist. Internet-based psychological treatments have shown to provide effective, accessible and affordable treatment for a range of anxiety disorders, and two Randomised Controlled Trials (RCTs) have demonstrated the efficacy and acceptability of internet-based CBT (iCBT) for OCD, as compared to waitlist or supportive therapy. Although these initial findings are promising, they do not isolate the specific effect of iCBT. This paper details the study protocol for the first randomised control trial evaluating the efficacy of therapist-assisted iCBT for OCD, as compared to a matched control intervention; internet-based therapist-assisted progressive relaxation training (iPRT). It will aim to examine whether therapist-assisted iCBT is an acceptable and efficacious treatment, and to examine how effectiveness is influenced by patient characteristics.

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Cognitive symptoms and impairment are central to schizophrenia and often an early sign of this condition. The present study investigated biological correlates of cognitive symptoms and performance in individuals at ultra-high risk (UHR) for psychosis. The study sample comprised 80 neuroleptic-naïve UHR individuals aged 13-25 years. Associations among erythrocyte membrane fatty acid levels, measured by gas chromatography, and cognitive functioning were investigated in UHR patients. Subjects were divided into terciles based on their scores on the cognitive factor of the Positive and Negative Syndrome Scale. The Zahlen-Verbindungs Test (ZVT) (the number-combination test) was also used as a measure of information-processing speed. Exploratory analysis was conducted to investigate the relationship between membrane fatty acid levels with the size of the intracranial area (ICA), a neurodevelopmental measure relevant to schizophrenia, in half of subjects (n=40) using magnetic resonance imaging. The adjusted analysis revealed that omega-9 eicosenoic and erucic acid levels were significantly higher, but omega-3 docosahexaenoic acid levels were significantly lower, in the cognitively impaired than in the cognitively intact group. We found a significant negative association of eicosenoic, erucic, and gamma-linoleic acids with ZVT scores. A negative association between ICA and membrane levels of eicosenoic acid was also found. This is the first study to demonstrate the relationship between membrane fatty acids and cognitive function in neuroleptic-naïve subjects at UHR for psychosis. The study findings indicate that abnormalities in membrane fatty acids may be associated with the neurodevelopmental disruption associated with the cognitive impairments of individuals at UHR for psychosis.

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With escalating health expenditure and a shrinking purse, there is increased focus on the cost efficacy of still patented versus generic medications in general, and for atypical antipsychotics in particular. In a recent BMC Medicine article, Godman and colleagues presented data indicating poor uptake of the off patent atypical antipsychotic risperidone, arguing for authorities to mandate its greater use. This is under the assumption of clinical equivalence of atypical antipsychotics. This commentary argues that there are clinically meaningful differences between atypical antipsychotics and important inter-individual heterogeneity in clinical response and tolerability. Access to a broad range of atypical antipsychotics enables clinicians to tailor care, taking consideration of differential efficacy and adverse effects profile in order to meet the needs of individual patients with improved real world effectiveness of treatment. Restriction of agent choice risks detracting from optimal clinical care, with possible poorer outcomes and greater costs of care. A balance between encouraging use of cheapest in class agent and allowing access to various atypical agents for tailored care is likely to produce optimal health outcomes.Please see related article: http://www.biomedcentral.com/1741-7015/12/98.

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Background: Emerging evidence supports a relationship between risk factors for obesity and the genesis of the common mental disorders, depression and anxiety. This suggests common mental disorders should be considered as a form of non-communicable disease, preventable through the modification of lifestyle behaviours, particularly diet and physical activity.Discussion: Obesity prevention research since the 1970's represents a considerable body of knowledge regarding strategies to modify diet and physical activity and so there may be clear lessons from obesity prevention that apply to the prevention of mental disorders. For obesity, as for common mental disorders, adolescence represents a key period of vulnerability. In this paper we briefly discuss relationships between modifiable lifestyle risk factors and mental health, lifestyle risk factor interventions in obesity prevention research, the current state of mental health prevention, and the implications of current applications of systems thinking in obesity prevention research for lifestyle interventions.Summary: We propose a potential focus for future mental health promotion interventions and emphasise the importance of lessons available from other lifestyle modification intervention programmes.

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Recent research suggests that diet quality influences depression risk; however, a lack of experimental evidence leaves open the possibility that residual confounding explains the observed relationships. The aim of this study was to document the cross-sectional and longitudinal associations between dietary patterns and symptoms of depression and to undertake a detailed examination of potential explanatory factors, particularly socioeconomic circumstances, in the diet-depression relationship.

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Worldwide, women fail to reach the recommended exclusive breastfeeding target of 6 months postpartum. The objective of this study was to present a conceptual and methodological synthesis of interventions designed to promote exclusive breastfeeding to 6 months in high-income countries.