193 resultados para EMPIRICAL-EVIDENCE


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The Australian home loan market has seen a significant and persistent boom over more than two decades. Theextant literature exploring the underlying factors explaining this boom has predominantly looked at thedemand side rather than the supply side. In this paper, we look at a major supply-side issue, the introductionof mortgage-backed securities and its likely impact on the home loan market. In doing so, we have developeda mathematical model that theorises this likely relationship. Our mathematical model predicts possibleexistence of an unstable equilibrium in the home loan market in the presence of mortgage-backed securities.We have subsequently backed up our theoretical exercise with sound empirical evidence acquired andanalysed as a natural experiment in the Australian scenario using quarterly market data on home loans andmortgage-backed securities data for a 36-year period from 1976 to 2012. Using unknown structural breaktests, we have identified significant breaks around late 1992 to mid-1995, clearly indicating that there weresignificant changes in the housing market due to the introduction of mortgage-backed securities in early1993. We have also performed a stability test confirming that under certain conditions this market canbecome unstable.

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We investigated the purported association between developmental changes in the efficiency of online reaching corrections and improved action representation. Younger children (6-7years), older children (8-12years), adolescents (13-17years), and young adults (18-24years) completed a double-step reaching paradigm and a motor imagery task. Results showed similar nonlinear performance improvements across both tasks, typified by substantial changes in efficiency after 6 or 7years followed by incremental improvements. Regression showed that imagery ability significantly predicted reaching efficiency and that this association stayed constant across age. Findings provide the first empirical evidence that more efficient online control through development is predicted, partly, by improved action representation.

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Some migratory birds refuel at stopover sites that they by-pass on the return trip. In theory, this skipping behaviour is only expected in time-selected migrants when the overflown site is of a lower quality than the departure site. We provide empirical evidence that quality differences in stopover sites are the cause for skipping in Bewick's Swans Cygnus bewickii tracked by satellite telemetry. Two and five complete tracks were recorded in spring and autunm, respectively, showing that the White Sea was visited for c. 2 weeks in spring, but by-passed (or visited for a few days at the most) in autumn. Skipping of the White Sea in autumn was predicted by a dynamic programming model which was based on calculated gain rates during stopover in the Pechora Delta and the White Sea. This prediction was not sensitive to plausible variations in gain rates. Relative to the Pechora Delta the White Sea is a poor site because a large tidal amplitude precludes foraging on the beds of the submerged macrophyte Fennel Pondweed Potamogeton pectinatus during high tide. The dynamic programming model predicted a fast autunm migration. However, the phenology of autunm arrival dates of Bewick's Swans on the wintering grounds revealed that only in three out of ten years a significant number of birds was able to reach the wintering grounds without refuelling. In the other years, unfavourable wind conditions along the Russian/Baltic part of the route prevented such non-stop migration.

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Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora) sediment C levels following seagrass (Thallasiatestudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m(2) mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m(2)). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation.

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This paper examines the influence of perceived organizational support and perceived supervisor support on employee life satisfaction. Structural equation modelling on data from 393 nurses from two Chinese hospitals revealed that job satisfaction fully mediated the relationship between perceived organizational support and life satisfaction. In contrast, perceived supervisor support had a direct influence on life satisfaction rather than a mediated influence through job satisfaction. Our findings highlight the importance of separating the locus of support constructs when examining the impact of support on job and life satisfaction, given that perceived support has different effects depending upon the transmitter of that support. © 2014 Springer Science+Business Media Dordrecht.

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BACKGROUND: Obesity in early childhood is a robust predictor of obesity later in life. Schools provide unparalleled access to children and have subsequently become major intervention sites. However, empirical evidence supporting the effectiveness of school-based interventions against childhood obesity is of limited scope and unknown quality. The aim of this systematic review is to critically assess how researchers have characterized the school environment in determining its effect on childhood weight status in order to improve the quality and consistency of research in this area. We conducted a narrative review with a systematic search of the literature in line with PRISMA guidelines (2009). Original peer-reviewed research articles in English were searched from Medline, EMBASE, CENTRAL, CINAHL and PsycINFO databases from earliest record to January 2014. We included empirical research that reported at least one measure of the primary/elementary school environment and its relationship with at least one objective adiposity-related variable for students aged 4-12 years. Two authors independently extracted data on study design, school-level factors, student weight status, type of analysis and effect. RESULTS: Five studies met the inclusion criteria. Each study targeted different parts of the school environment and findings across the studies were not comparable. The instruments used to collect school-level data report no validity or reliability testing. CONCLUSIONS: Our review shows that researchers have used instruments of unknown quality to test if the school environment is a determinant of childhood obesity, which raises broader questions about the impact that schools can play in obesity prevention.

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FDI is seen widely as a vital source of investment, technology transfer, and growth. The factors that attract FDI have been a longstanding source of debate. The authors present a comprehensive assessment of the accumulated evidence on one factor, the success of economic growth in attracting FDI. Meta-regression analysis is applied to 946 estimates from 140 empirical studies. The results confirm that, on average, economic growth is an important determinant of FDI. Overall, there is a positive correlation between growth and FDI and this is much larger among single country case studies than with cross-country analysis.

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Most empirical evidence suggests that the Fisher effect, stating that inflation and nominal interest rates should cointegrate with a unit slope on inflation, does not hold, a finding at odds with many theoretical models. This paper argues that these results can be attributed in part to the low power of univariate tests, and that the use of panel data can generate more powerful tests. For this purpose, we propose two new panel cointegration tests that can be applied under very general conditions, and that are shown by simulation to be more powerful than other existing tests. These tests are applied to a panel of quarterly data covering 20 OECD countries between 1980 and 2004. The evidence suggest that the Fisher effect cannot be rejected once the panel evidence on cointegration has been taken into account. Copyright © 2008 John Wiley & Sons, Ltd.

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This paper will test the core claim of scholars in the nexus of contracts tradition—that private ordering as a process of bargaining creates optimal rules. We do this by analyzing empirical evidence in the context of waiver of liability provisions. These provisions allow companies to eliminate monetary damages for breach of the duty of care through amendments to the articles of incorporation. With all states allowing some form of these provisions, they represent a good laboratory to examine the bargaining process between management and shareholders. The contractarian approach would suggest that shareholders negotiate with management to obtain agreements that are in their best interests. If a process of bargaining is at work as they claim, the opt-in process for waiver of liability provisions ought to generate a variety of approaches. Shareholders wanting a high degree of accountability would presumably not support a waiver of liability. In other instances, shareholders might favor them in order to attract or retain qualified managers. Still others would presumably want a mix, allowing waiver but only in specified circumstances.Our analysis reveals that the diversity predicted by a private ordering model is not borne out by the evidence with waiver of liability provisions for Fortune 100 companies. All states permit such provisions and in the Fortune 100, all but one company has them. Moreover, they are remarkably similar in effect, waiving liability to the fullest extent permitted by law. In other words, one categorical rule was merely replaced by another, dealing a significant blow to the contractarian thesis.

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Most empirical evidence suggests that the sustainability hypothesis, stating that government revenues and expenditures should cointegrate with a unit slope on expenditures, does not hold within the European Union, a finding at odds with many theoretical models. This paper argues that these results can be attributed in part to the use of in-appropriate time-series techniques, and that the use of panel data can generate more accurate tests. By using newly devised panel unit-root and cointegration techniques it is shown that the sustainability hypothesis cannot be rejected when applied to a panel composed of 15 European countries between 1970 and 2004. © 2009 Mohr Siebeck.

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The koala (Phascolarctos cinereus), one of the world's most iconic faunal species, was recently listed under Australian government legislation as vulnerable in the northern states of Queensland and New South Wales and in the Australian Capital Territory, but not in the southern states of Victoria and South Australia. This review synthesises empirical evidence of regional koala population trends, their conservation outlook, and associated policy challenges. Population declines are common in the northern half of the koala's range, where habitat loss, hotter droughts, disease, dog attacks and vehicle collisions are the major threats. In contrast, some southern populations are locally overabundant and are now subject to managed declines. The koala presents the problem of managing a wide-ranging species that now primarily occurs in human-modified landscapes, some of which are rapidly urbanising or subject to large-scale agricultural and mining developments. Climate change is a major threat to both northern and southern populations. The implementation of policy to conserve remaining koala habitat and restore degraded habitat is critical to the success of koala conservation strategies, but habitat conservation alone will not resolve the issues of koala conservation. There needs to be concerted effort to reduce the incidence of dog attack and road-related mortality, disease prevalence and severity, and take into account new threats of climate change and mining. Many of the complex conservation and policy challenges identified here have broader significance for other species whose population trends, and the nature of the threatening processes, vary from region to region, and through time.

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BACKGROUND: Physical activity is a modifiable behavior related to many preventable non-communicable diseases. There is an age-related decline in physical activity levels in young people, which tracks into adulthood. Common interactive technologies such as smartphones, particularly employing immersive features, may enhance the appeal and delivery of interventions to increase levels of physical activity in young people. The primary aim of the Apps for IMproving FITness (AIMFIT) trial is to evaluate the effectiveness of two popular "off-the-shelf" smartphone apps for improving cardiorespiratory fitness in young people.

METHODS/DESIGN: A three-arm, parallel, randomized controlled trial will be conducted in Auckland, New Zealand. Fifty-one eligible young people aged 14-17 years will be randomized to one of three conditions: 1) use of an immersive smartphone app, 2) use of a non-immersive app, or 3) usual behavior (control). Both smartphone apps consist of an eight-week training program designed to improve fitness and ability to run 5 km, however, the immersive app features a game-themed design and adds a narrative. Data are collected at baseline and 8 weeks. The primary outcome is cardiorespiratory fitness, assessed as time to complete the one mile run/walk test at 8 weeks. Secondary outcomes are physical activity levels, self-efficacy, enjoyment, psychological need satisfaction, and acceptability and usability of the apps. Analysis using intention to treat principles will be performed using regression models.

DISCUSSION: Despite the proliferation of commercially available smartphone applications, there is a dearth of empirical evidence to support their effectiveness on the targeted health behavior. This pragmatic study will determine the effectiveness of two popular "off-the-shelf" apps as a stand-alone instrument for improving fitness and physical activity among young people. Adherence to app use will not be closely controlled; however, random allocation of participants, a heterogeneous group, and data analysis using intention to treat principles provide internal and external validity to the study. The primary outcome will be objectively assessed with a valid and reliable field-based test, as well as the secondary outcome of physical activity, via accelerometry. If effective, such applications could be used alongside existing interventions to promote fitness and physical activity in this population. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12613001030763. Registered 16 September 2013.

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Central bank communication has become a more and more important instrument for the monetary authorization to intervene its exchange rate. This paper investigates the impact of both verbal and actual intervention on the exchange rate of China's currency, which has become the second-used currency in international trade settlement. The empirical evidence indicates that the central bank communication can influence the exchange rate, but the efficient is quite weak. Moreover, the effect of verbal intervention on the exchange rate of the RMB is weaker than that of actual intervention. One possible explanation is that most of the statements made by the governor of central bank on the RMB exchange rate are neutral in China. Overall, this study identifies the difference between the actual and verbal intervention in exchange rate in China, the largest emerging economy in the world.