66 resultados para EMPIRICAL-EVIDENCE


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It has been 25 years since the publication of a comprehensive review of the full spectrum of salesperformance drivers. This study takes stock of the contemporary field and synthesizes empirical evidence from the period 1982–2008. The authors revise the classification scheme for sales performance determinants devised by Walker et al. (1977) and estimate both the predictive validity of its sub-categories and the impact of a range of moderators on determinant-sales performance relationships. Based on multivariate causal model analysis, the results make two major observations: (1) Five sub-categories demonstrate significant relationships with sales performance: selling-related knowledge (ß=.28), degree of adaptiveness (ß=.27), role ambiguity (ß=-.25), cognitive aptitude (ß=.23) and work engagement (ß=.23). (2) These sub-categories are moderated by measurement method, research context, and salestype variables. The authors identify managerial implications of the results and offer suggestions for further research, including the conjecture that as the world is moving toward a knowledge-intensive economy, salespeople could be functioning as knowledge-brokers. The results seem to back this supposition and indicate how it might inspire future research in the field of personal selling.

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Aim: Species loss has increased significantly over the last 1000 years and is ultimately attributed to the direct and indirect consequences of increased human population growth across the planet. A growing number of species are becoming endangered and require human intervention to prevent their local extirpation or complete extinction. Management strategies aimed at mitigating a species loss can benefit greatly from empirical approaches that indicate the rate of decline of a species providing objective information on the need for immediate conservation actions, e.g. captive breeding; however, this is rarely employed. The current study used a novel method to examine the distributional trends of a model endangered species, the freshwater pearl mussel, Margaritifera margaritifera (L.).
Location: United Kingdom and Republic of Ireland.
Methods: Using species presence data within 10-km grid squares since records began three-parameter logistic regression curves were fitted to extrapolate an estimated date of regional extinction.
Results: This study has shown that freshwater pearl mussel distribution has contracted since known historical records and outlier populations were lost first. Within the United Kingdom and Republic of Ireland, distribution loss has been greatest in Scotland, Northern Ireland, Wales and England, respectively, with the Republic of Ireland containing the highest relative proportion of M. margaritifera distribution, in 1998.
Main conclusions: This study provides empirical evidence that this species could become extinct throughout countries within the United Kingdom within 170 years under the current trends and emphasizes that regionally specific management strategies need to be implemented to prevent extirpation of this species.

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The pattern of predator-prey interactions is thought to be a key determinant of ecosystem processes and stability. Complex ecological networks are characterized by distributions of interaction strengths that are highly skewed, with many weak and few strong interactors present. Theory suggests that this pattern promotes stability as weak interactors dampen the destabilizing potential of strong interactors. Here, we present an experimental test of this hypothesis and provide empirical evidence that the loss of weak interactors can destabilize communities in nature. We ranked 10 marine consumer species by the strength of their trophic interactions. We removed the strongest and weakest of these interactors from experimental food webs containing >100 species. Extinction of strong interactors produced a dramatic trophic cascade and reduced the temporal stability of key ecosystem process rates, community diversity and resistance to changes in community composition. Loss of weak interactors also proved damaging for our experimental ecosystems, leading to reductions in the temporal and spatial stability of ecosystem process rates, community diversity, and resistance. These results highlight the importance of conserving species to maintain the stabilizing pattern of trophic interactions in nature, even if they are perceived to have weak effects in the system.

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We investigate whether low-priced stocks drive long-term contrarian performance on the U.K. market. We find that contrarian performance at low, middle, and high price levels is positive. On the Fama-French risk adjusted basis, we find both low-priced and middle-priced losers have significantly positive returns. When we adjust returns by market and liquidity risk, only middle-priced losers maintain their positive returns. Our results reveal that low-priced stocks are not fully responsible for contrarian performance. Our empirical evidence is generally consistent with the overreaction hypothesis and behavioral models of value investing.

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Purpose The UK government argues that the benefits of public private partnership (PPP) in delivering public infrastructure stem from: transferring risks to the private sector within a structure in which financiers put their own capital at risk; and, the performance based payment mechanism, reinforced by the due diligence requirements imposed by the lenders financing the projects (HM Treasury, 2010). Prior studies of risk in PPPs have investigated ‘what’ risks are allocated and to ‘whom’, that is to the public or the private sector. The purpose of this study is to examine ‘how’ and ‘why’ PPP risks are diffused by their financiers. Design/methodology/approach This study focuses on the financial structure of PPPs and on their financiers. Empirical evidence comes from interviews conducted with equity and debt financiers. Findings The findings show that the financial structure of the deals generates risk aversion in both debt and equity financiers and that the need to attract affordable finance leads to risk diffusion through a network of companies using various means that include contractual mitigation through insurance, performance support guarantees, interest rate swaps and inflation hedges. Because of the complexity this process generates, both procurers and suppliers need expensive expert advice. The risk aversion and diffusion and the consequent need for advice add cost to the projects impacting on the government’s economic argument for risk transfer. Limitations and implications The empirical work covers the private finance initiative (PFI) type of PPP arrangements and therefore the risk diffusion mechanisms may not be generalisable to other forms of PPP, especially those that do not involve the use of high leverage or private finance. Moreover, the scope of this research is limited to exploring the diffusion of risk in the private sector. Further research is needed on how risk is diffused in other settings and on the value for money implication of risk diffusion in PPP contracts. Originality/value The expectation inherent in PPP is that the private sector will better manage those risks allocated to it and because private capital is at risk, financiers will perform due diligence with the ultimate outcome that only viable projects will proceed. This paper presents empirical evidence that raises questions about these expectations. Key words: public private partnership, risk management, diffusion, private finance initiative, financiers

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Although variation in body size has been recently reported in stingless bees (Meliponini), empirical evidence evaluating possible factors related to such variation is lacking, and thus it is not clear if it may have an adaptive significance. We evaluated if variation in the body size and weight of workers of stingless bees fluctuates across a seasonal pattern and if this could be related to characteristics of the food consumed during the larval stage. The weight of larval provisions, their protein, and sugar content were evaluated in four colonies of Nannotrigona perilampoides every 2 months across 1 year. Worker-destined larvae from the same combs were allowed to develop and were sampled as callow workers to determine their weight and size using morphometric data. The weight and size of workers were highly correlated and varied across the seasons in established colonies, suggesting that size variation cycles across the year in stingless bees. An increase in the protein content and, to a lesser degree, the quantity of larval food were positively linked to variation in body weight and size; food with richer protein content resulted in larger and heavier workers. This study provides the first evidence of an effect of the quantity and composition of larval food on the size of workers in stingless bees. Although body weight and size of workers differed across seasons, they were not readily noticeable as changes seem to occur as a continuum across the year. Since size polymorphism was of a larger magnitude across time but not within age cohorts and as it was highly determined by food resources, it may not be an adaptive feature in stingless bees. However, more studies are needed to determine the role of the cyclical change in worker body size on colony performance and thus its adaptive significance in stingless bees.

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This article describes the development, organization, and operation of the Campbell Collaboration, an international network of academics and practitioners who prepare, maintain, and make accessible authoritative systematic reviews of the effectiveness of interventions in the fields of social welfare, education, and criminal justice. The Campbell Collaboration is modeled after the successful Cochrane Collaboration, established in 1993 to produce reviews of the evidence relating to the effectiveness of services in the field of health care. The aim of such reviews is to provide practitioners with a summary of the best available empirical evidence on which to base practice decisions.

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Aims. This article is a report of a trial protocol to determine if improvizational music therapy leads to clinically significant improvement in communication and interaction skills for young people experiencing social, emotional or behavioural problems. Background. Music therapy is often considered an effective intervention for young people experiencing social, emotional or behavioural difficulties. However, this assumption lacks empirical evidence. Study design. Musicinmindisamulti-centredsingle-blindrandomizedcontrolledtrial involving 200 young people (aged 8–16 years) and their parents. Eligible participants willhaveaworkingdiagnosiswithintheambitofInternational ClassificationofDisease 10 Mental and Behavioural Disorders and will be recruited over 15 months from six centres within the Child and Adolescent Mental Health Services of a large health and social care trust in Northern Ireland. Participants will be randomly allocated in a 1:1 ratio to receive standard care alone or standard care plus 12 weekly music therapy sessions delivered by the Northern Ireland Music Therapy Trust. Baseline data will be collectedfromyoungpeopleandtheirparentsusingstandardizedoutcomemeasuresfor communicative and interaction skills (primary endpoint), self-esteem, social functioning, depressionandfamilyfunctioning.Follow-updatawillbecollected1and13 weeks afterthefinalmusictherapysession.Acost-effectivenessanalysiswillalsobecarriedout. Discussion. This study will be the largest trial to date examining the effect of music therapy on young people experiencing social, emotional or behavioural difficulties and will provide empirical evidence for the use of music therapy among this population. Trial registration. This study is registered in theISRCTNRegister,ISRCTN96352204. Ethical approval was gained in October 2010.

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Loss of biodiversity and nutrient enrichment are two of the main human impacts on ecosystems globally, yet we understand very little about the interactive effects of multiple stressors on natural communities and how this relates to biodiversity and ecosystem functioning. Advancing our understanding requires the following: (1) incorporation of processes occurring within and among trophic levels in natural ecosystems and (2) tests of context-dependency of species loss effects. We examined the effects of loss of a key predator and two groups of its prey on algal assemblages at both ambient and enriched nutrient conditions in a marine benthic system and tested for interactions between the loss of functional diversity and nutrient enrichment on ecosystem functioning. We found that enrichment interacted with food web structure to alter the effects of species loss in natural communities. At ambient conditions, the loss of primary consumers led to an increase in biomass of algae, whereas predator loss caused a reduction in algal biomass (i.e. a trophic cascade). However, contrary to expectations, we found that nutrient enrichment negated the cascading effect of predators on algae. Moreover, algal assemblage structure varied in distinct ways in response to mussel loss, grazer loss, predator loss and with nutrient enrichment, with compensatory shifts in algal abundance driven by variation in responses of different algal species to different environmental conditions and the presence of different consumers. We identified and characterized several context-dependent mechanisms driving direct and indirect effects of consumers. Our findings highlight the need to consider environmental context when examining potential species redundancies in particular with regard to changing environmental conditions. Furthermore, non-trophic interactions based on empirical evidence must be incorporated into food web-based ecological models to improve understanding of community responses to global change.

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In recent years there has been a remarkable surge of interest in the concept of punitiveness in theoretical criminology. Accounts serve to emphasise rupture over continuity, drawing attention to the increased focus on managerialism, risk and expressive penal policies in countries such as England and the US. Criticisms of these accounts have drawn attention to the weak empirical base for such assertions and the continued relevance of local cultural, historical and political conditions in mediating the effect of more punitive trends. In light of the relative neglect of smaller jurisdictions in this literature it was decided to locate these debates in three small common law jurisdictions, namely, Ireland, Scotland and New Zealand over the period 1976-2006 with a view to assessing the empirical evidence for penal change. This was done using a broader definition of punitiveness than normally employed incorporating indices relating to the ‘front end’ (eg police powers) as well as the ‘back end’ (eg prison and probation) of the criminal justice system. Data were collected on the three case studies using a multi-method approach involving examination of extensive quantitative data, interviews with key criminal justice stakeholders and documentary analysis. The data provide some support for the ‘new punitiveness’ thesis in these countries through a pattern of increased legislative activity aimed at controlling violent and sexual offenders and significant increases in the lengths of sentences imposed. However, analysis of qualitative data and a larger number of variables reveals distinctly different patterns of punitiveness over the thirty year period in the three countries. It is argued that the study holds important lessons for comparative criminology into the ‘new punitiveness’. There is a need for qualitative as well as quantitative data; for multiple rather than singular indices across a wide range of areas (juvenile justice, prison conditions, etc); and for ‘front end’ as well as ‘back end’ indices.

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Although it is widely believed that one of the key factors influencing whether an adolescent smokes or not is the smoking behaviour of his or her peers, empirical evidence on the magnitude of such peer effects, and even on their existence, is mixed. This existing evidence comes from a range of studies using a variety of country-specific data sources and a variety of identification strategies. This paper exploits a rich source of individual level, school-based, survey data on adolescent substance use across countries - the 2007 European Schools Survey Project on Alcohol and Other Drugs - to provide estimates of peer effects between classmates in adolescent smoking for 75,000 individuals across 26 European countries, using the same methods in each case. The results suggest statistically significant peer effects in almost all cases. These peer effects estimates are large: on average across countries, the probability that a 'typical' adolescent smokes increases by between.31 and.38 percentage points for a one percentage point increase in the proportion of classmates that smoke. Further, estimated peer effects in adolescent smoking are stronger intra-gender than inter-gender. They also vary across countries: in Belgium, for example, a one percentage point increase in reference group smoking is associated with a.16 to.27 percentage point increase in own smoking probability; in the Netherlands the corresponding increase is between.42 and.59 percentage points. © 2011 Elsevier Ltd.

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The literature on Social exclusion has focused attention on the processes leading to exposure to multiple disadvantage. Despite the influence this perspective has had on both academic and policy discussions, conceptual analysis has remained imprecise and empirical evidence modest. We have made use of the European Community Household Panel (ECHP) in order to examine the extent to which persistent income poverty results in multiple deprivation. Our analysis shows that only a modest proportion of the persistently poor can he characterized as being exposed to such deprivation. While persistent poverty and multiple deprivation combine to produce extremely high levels of economic strain, there is no evidence that they interact in a significant fashion. We argue that understanding deprivation is not facilitated by focusing on a cleavage between a multiply deprived minority and a comfortable majority, and we consider the policy implications of this argument.

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Meeting the supportive care needs of cancer patients remains a challenge to cancer care systems around the world. Despite significant improvements in the organization of medical care of patients with cancer, numerous surveys of cancer populations demonstrate that significant proportions of patients fail to have their supportive care needs met. One possible solution is the introduction of a care coordinator role using oncology nursing to help ensure that patients' physical, psychological, and social support needs are addressed. Although having face validity, there is little empirical evidence on the effects of nurse-led supportive care coordinator roles on patient reported supportive care outcomes. In this article the authors present the results of a prospective longitudinal cohort study of 113 patients referred to a community-based specialist oncology nursing program. Using validated instruments they found significant improvements in patient-reported outcomes in key supportive care domains: unmet needs, quality of life, and continuity of care, as well as a shift in patterns of health resource utilization from acute care settings to the community over the course of the intervention. The results of this study are important in supporting the design and development of controlled trials to examine provider roles in the coordination of supportive cancer care. Copyright © Taylor & Francis Group, LLC.

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We present empirical evidence about the properties of economic sentiment cycle synchronization for Germany, France and the UK and compare them with the `crisis' countries Italy, Spain, Portugal and Greece. Instead of using output data we prefer to focus on the economic sentiment indicator (ESI), a forward-looking, survey-based variable consistently available from 1985. The cyclical nature of the ESI allows us to analyze the presence or not of synchronicity among country pairs before and after the onset of the financial crisis. Our results show that ESI movements were mostly synchronous before 2008 but they exhibit a breakdown after 2008, with this feature being more prominent in Greece. We also find that, after the political manoeuvring of the past two years, a cycle re-integration or re-synchronization is on the way. An analysis of the evolution of the synchronicity measures indicates that they can potentially be used to identify sudden phase breaks in ESI co-movement and they can offer a signal as to when the EU economies are getting “in” or “out of sync”.

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Health professionals are expected to support family caregivers of patients requiring palliative care. However, there is a dearth of empirical evidence to help clinicians identify caregivers who might be at risk of poor psychosocial functioning.