20 resultados para Intensive longitudinal design


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Socioeconomic considerations should have an important place in reserve design, Systematic reserve-selection tools allow simultaneous optimization for ecological objectives while minimizing costs but are seldom used to incorporate socioeconomic costs in the reserve-design process. The sensitivity of this process to biodiversity data resolution has been studied widely but the issue of socioeconomic data resolution has not previously been considered. We therefore designed marine reserves for biodiversity conservation with the constraint of minimizing commercial fishing revenue losses and investigated how economic data resolution affected the results. Incorporating coarse-resolution economic data from official statistics generated reserves that were only marginally less costly to the fishery than those designed with no attempt to minimize economic impacts. An intensive survey yielded fine-resolution data that, when incorporated in the design process, substantially reduced predicted fishery losses. Such an approach could help minimize fisher displacement because the least profitable grounds are selected for the reserve. Other work has shown that low-resolution biodiversity data can lead to underestimation of the conservation value of some sites, and a risk of overlooking the most valuable areas, and we have similarly shown that low-resolution economic data can cause underestimation of the profitability of some sites and a risk of inadvertently including these in the reserve. Detailed socioeconomic data are therefore an essential input for the design of cost-effective reserve networks.

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Many variables that are of interest in social science research are nominal variables with two or more categories, such as employment status, occupation, political preference, or self-reported health status. With longitudinal survey data it is possible to analyse the transitions of individuals between different employment states or occupations (for example). In the statistical literature, models for analysing categorical dependent variables with repeated observations belong to the family of models known as generalized linear mixed models (GLMMs). The specific GLMM for a dependent variable with three or more categories is the multinomial logit random effects model. For these models, the marginal distribution of the response does not have a closed form solution and hence numerical integration must be used to obtain maximum likelihood estimates for the model parameters. Techniques for implementing the numerical integration are available but are computationally intensive requiring a large amount of computer processing time that increases with the number of clusters (or individuals) in the data and are not always readily accessible to the practitioner in standard software. For the purposes of analysing categorical response data from a longitudinal social survey, there is clearly a need to evaluate the existing procedures for estimating multinomial logit random effects model in terms of accuracy, efficiency and computing time. The computational time will have significant implications as to the preferred approach by researchers. In this paper we evaluate statistical software procedures that utilise adaptive Gaussian quadrature and MCMC methods, with specific application to modeling employment status of women using a GLMM, over three waves of the HILDA survey.

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Email has been used for some years as a low-cost telemedicine medium to provide support for developing countries. However, all operations have been relatively small scale and fairly labour intensive to administer. A scalable, automatic message-routing system was constructed which automates many of the tasks. During a four-month study period in 2002, 485 messages were processed automatically. There were 31 referrals from eight hospitals in three countries. These referrals were handled by 25 volunteer specialists from a panel of 42. Two system operators, located 10 time zones apart, managed the system. The median time from receipt of a new referral to its allocation to a specialist was 1.0 days (interquartile range 0.7-2.4). The median interval between allocation and first reply was 0.7 days (interquartile range 0.3-2.3). Automatic message handling solves many of the problems of manual email telemedicine systems and represents a potentially scalable way of doing low-cost telemedicine in the developing world.

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This research seeks to generate and foster new descriptions and understandings of processes underlying the internationalisation experienced by small- and medium-sized, knowledge-intensive enterprises. The longitudinal study centres on the growth and internationalisation of a cluster of small- and medium-sized enterprises (SMEs) in the most southern state of Australia, of which a number were 'bom global.' It draws on both retrospective data such as corporate archives, as well as observations and interviews as events unfolded over a period of eighteen months to garner insights into processes underlying the SMEs' internationalisation. The approach to inquiry is influenced by an epistemology of social constructionism, interpretive narrative, sensemaking and dramaturgical theoretical perspectives, and elements of cultural anthropology. Exploratory in the early stages, a funnel approach characteristic of ethnographic enquiry was used whereby the study became progressively focused over time. The extended period of fieldwork led to observations and interpretations that cast the retrospective data in new light, and the use of the construct 'legitimacy' as a lens through which to view activities and events infusing the firms' internationalisation. A generic narrative scheme that offers a temporal ordering of actions, context and meaning attributions in relation to legitimation behaviours and internationalisation processes is developed. This narrative scheme is then used to garner a deeper understanding of three activities that were central to the firms' internationalisation over time: the choice of geographic export markets, strategic participation in international standard-setting committees, and portfolio entrepreneurship. In addition, the study offers a rich story of the growth and internationalisation of the cluster of knowledge-intensive SMEs. The tale of growth and internationalisation pursued by the cluster of knowledgeintensive SMEs spans the period from 1975 to mid 1997, and may prove a useful resource for the theorising of others.