77 research outputs found

    ON THE PERFORMANCE OF NONPARAMETRIC SPECIFICATION TESTS IN REGRESSION MODELS

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    Some recently developed nonparametric specification tests for regression models are described in a unified way. The common characteristic of these tests is that they are consistent against any alternative hypothesis. The performance of the test statistics is compared by means of Monte Carlo simulations, analysing how heteroskedasticity, number of regressors and bandwidth selection influence the results. The statistics which do not use a bandwidth perform slightly better if the regression model has only one regressor; otherwise, some of the statistics which use a bandwidth behave better if the bandwidth is chosen adequately. These statistics are applied to test the specification of three commonly used Mincer-type wage equations with Uruguayan and Spanish data; all of them are rejected.

    Overeducation across British regions

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    This paper analyses levels of over-education and wage returns to education for males across eleven regions of the UK using Labour Force Survey data. Significant differences are found in the probability of being over-educated across regions; also, differences are found in the return to the ‘correct’ level of education in each region, in each case associated with flexibility of movement between and into particular regions, which determines the ease of job matching. Furthermore, evidence is found that, after controlling for the level of education acquired, there exists a premium to the ‘correct’ level of education, which varies across UK regions

    Reducing the environmental impact of trials: a comparison of the carbon footprint of the CRASH-1 and CRASH-2 clinical trials

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    BACKGROUND: All sectors of the economy, including the health research sector, must reduce their carbon emissions. The UK National Institute for Health Research has recently prepared guidelines on how to minimize the carbon footprint of research. We compare the carbon emissions from two international clinical trials in order to identify where emissions reductions can be made. METHODS: We conducted a carbon audit of two clinical trials (the CRASH-1 and CRASH-2 trials), quantifying the carbon dioxide emissions produced over a one-year audit period. Carbon emissions arising from the coordination centre, freight delivery, trial-related travel and commuting were calculated and compared. RESULTS: The total emissions in carbon dioxide equivalents during the one-year audit period were 181.3 tonnes for CRASH-1 and 108.2 tonnes for CRASH-2. In total, CRASH-1 emitted 924.6 tonnes of carbon dioxide equivalents compared with 508.5 tonnes for CRASH-2. The CRASH-1 trial recruited 10,008 patients over 5.1 years, corresponding to 92 kg of carbon dioxide per randomized patient. The CRASH-2 trial recruited 20,211 patients over 4.7 years, corresponding to 25 kg of carbon dioxide per randomized patient. The largest contributor to emissions in CRASH-1 was freight delivery of trial materials (86.0 tonnes, 48% of total emissions), whereas the largest contributor in CRASH-2 was energy use by the trial coordination centre (54.6 tonnes, 30% of total emissions). CONCLUSIONS: Faster patient recruitment in the CRASH-2 trial largely accounted for its greatly increased carbon efficiency in terms of emissions per randomized patient. Lighter trial materials and web-based data entry also contributed to the overall lower carbon emissions in CRASH-2 as compared to CRASH-1. TRIAL REGISTRATION NUMBERS: CRASH-1: ISRCTN74459797CRASH-2: ISRCTN86750102

    Advanced reliability analysis of Polymer Electrolyte Membrane Fuel Cells using Petri-Net analysis and fuel cell modelling techniques

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    This is the author’s version of a work that was accepted for publication in International Journal of Hydrogen Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.ijhydene.2015.01.154Reliability issues with fuel cells have held back the commercialisation of this new technology, and as such are required to be studied further. Current reliability standards for automotive applications require an operational life- time of 150,000 miles or 5,000 hours. These standards are hard to achieve; therefore in depth reliability analysis and degradation studies can help allude towards the key areas of improvement in fuel cell technology to meet these standards. Previous Failure Mode and Effect Analysis (FMEA) work has shown that the multi-component system of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) is inherently complex. Dependencies exist between multiple failure modes which discounts Fault Tree Analysis (FTA) as a feasible reliability modelling technique. Therefore, in this study, Petri-Net simulation and fuel cell modelling techniques have been adopted to develop an accurate degradation model. Operational parameters such as water content, temperature and current density and their effects on the occurrence of failure modes can be modelled through this technique. The work will improve previous fuel cell reliability studies by taking into consideration; operating parameters (water content, temperature), fuel cell voltage based on demand (drive cycles) and dependencies between failure modes

    Environmental impacts of food retail: A framework method and case application

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    © 2015 Elsevier Ltd. The food retail sector is the gatekeeper between consumers and producers and has substantial influence on consumption and production choices via procurement and provision decisions. Food provision and consumption systems embody huge environmental impacts worldwide. Food retailers as gatekeepers have a key role to play to enable sustainable consumption and provision to become common practice. In this paper, a framework to attribute emissions and water use to individual and all food retail businesses and their products by geographical area and postcode of cities is presented. As far as the current authors are aware, such a framework has not been generated for food retail sector businesses before, primarily due to barriers to input-output modelling of the sector. The scientific value added is that a novel approach to overcome barriers is presented as well as the required framework. The framework is illustrated for Southampton, but can be applied in other regions of the world where similar data exist. The value of a business's product emissions estimates (generated by the framework) is they can be a first step in informing product prioritisation for focussing information searches or more detailed life cycle analysis to make sustainable procurement and choice editing decisions. The approach has value to government, businesses and non-government organisations (NGOs) in developing strategy and planning sustainable provision and procurement; by helping benchmark sustainable shopping provision, prioritisation of retail businesses and product categories for sustainable procurement/choice editing

    Rationale, design and methods of the Study of Work and Pain (SWAP): a cluster randomised controlled trial testing the addition of a vocational advice service to best current primary care for patients with musculoskeletal pain (ISRCTN 52269669)

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    Background Musculoskeletal pain is a major contributor to short and long term work absence. Patients seek care from their general practitioner (GP) and yet GPs often feel ill-equipped to deal with work issues. Providing a vocational case management service in primary care, to support patients with musculoskeletal problems to remain at or return to work, is one potential solution but requires robust evaluation to test clinical and cost-effectiveness. Methods/Design This protocol describes a cluster randomised controlled trial, with linked qualitative interviews, to investigate the effect of introducing a vocational advice service into general practice, to provide a structured approach to managing work related issues in primary care patients with musculoskeletal pain who are absent from work or struggling to remain in work. General practices (n = 6) will be randomised to offer best current care or best current care plus a vocational advice service. Adults of working age who are absent from or struggling to remain in work due to a musculoskeletal pain problem will be invited to participate and 330 participants will be recruited. Data collection will be through patient completed questionnaires at baseline, 4 and 12 months. The primary outcome is self-reported work absence at 4 months. Incremental cost-utility analysis will be undertaken to calculate the cost per additional QALY gained and incremental net benefits. A linked interview study will explore the experiences of the vocational advice service from the perspectives of GPs, nurse practitioners (NPs), patients and vocational advisors. Discussion This paper presents the rationale, design, and methods of the Study of Work And Pain (SWAP) trial. The results of this trial will provide evidence to inform primary care practice and guide the development of services to provide support for musculoskeletal pain patients with work-related issues. Trial registration Current Controlled Trials ISRCTN52269669

    Can participatory emissions budgeting help local authorities to tackle climate change?

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    A lack of concerted action on the part of local authorities and their citizens to respond to climate change is argued to arise partly from a poor relationship between the two. Meanwhile, local authorities could have a significant impact on community-wide levels of greenhouse gas emissions because of their influence over many other actors, but have had limited success with orthodox voluntary behaviour change methods and hold back from stricter behaviour change interventions. Citizen participation may offer an effective means of improving understanding between citizens and government concerning climate change and, because it is inherently a dialogue, avoids many of the pitfalls of more orthodox attempts to effect behaviour change. Participatory budgeting is a form of citizen participation which seems well suited to the task in being quantitative, drawing a diverse audience and, when successfully run, engendering confidence amongst authority stakeholders. A variant of it, participatory emissions budgeting, would introduce the issue of climate change in a way that required citizens to trade off greenhouse gas emissions with wider policy goals. It may help citizens to appreciate the nature of the challenge and the role of local government in responding; this may in turn provide authority stakeholders with increased confidence in the scope to implement pro-environmental agendas without meeting significant resistance
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