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| Drouineau, Hilaire; Lobry, Jeremy; Delpech, C.; Bouchoucha, Marc; Mahevas, Stephanie; Courrat, A.; Pasquaud, S.; Lepage, M.. |
| In the context of the European Water Framework Directive (WFD), monitoring programs and related indicators have been developed to assess anthropogenic impacts on various components of aquatic ecosystems. While great precautions are usually taken when selecting and calculating relevant core metrics, little attention is generally paid to the generation of the multimetric indicator, i.e. the combination of the different core metrics. Indeed, most multimetric indicators are generated by simply averaging or summing metrics, without taking into account their sensitivity and their variability. Moreover, few indicators provide a rigorous estimate of the uncertainty of the assessments, while this estimation is essential for managers. In this context, we developed a... |
| Tipo: Text |
Palavras-chave: Multimetric fish-based indicator; Bayesian method; Pressure-impact models; Water Framework Directive; Anthropogenic pressure; Monitoring program; Transitional waters. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00049/16037/13572.pdf |
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| Tableau, Adrien; Drouineau, Hilaire; Delpech, C.; Pierre, M.; Lobry, J.; Le Pape, O.; Breine, J.; Lepage, Mario. |
| In the Water Framework Directive (European Union) context, a multimetric fish based index is required to assess the ecological status of French estuarine water bodies. A first indicator called ELFI was developed, however similarly to most indicators, the method to combine the core metrics was rather subjective and this indicator does not provide uncertainty assessment. Recently, a Bayesian method to build indicators was developed and appeared relevant to select metrics sensitive to global anthropogenic pressure, to combine them objectively in an index and to provide a measure of uncertainty around the diagnostic. Moreover, the Bayesian framework is especially well adapted to integrate knowledge and information not included in surveys data. In this context,... |
| Tipo: Text |
Palavras-chave: Anthropogenic pressure; Bayesian method; Expert judgement; Multimetric fish-based indicator; Prior information; Water Framework Directive. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00146/25700/24029.pdf |
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| Lowe, John J.; Blockley, Simon; Trincardi, Fabio; Asioli, Alessandra; Cattaneo, Antonio; Matthews, I. P.; Pollard, M.; Wulf, S.. |
| The first part of this paper presents a review of the problems that constrain the reliability of radiocarbon-based age models with particular focus on those used to underpin marine records. The reasons why radiocarbon data-sets need to be much more comprehensive than has been the norm hitherto, and why age models should be based on calibrated data only, are outlined. The complexity of the probability structure of calibrated radiocarbon data and the advantages of a Bayesian statistical approach for constructing calibrated age models are illustrated. The second part of the paper tests the potential for reducing the uncertainties that constrain radiocarbon-based age models using tephrostratigraphy. Fine (distal) ash layers of Holocene age preserved in... |
| Tipo: Text |
Palavras-chave: Radiocarbon-based age models; Tephrochronology; Volcanic event stratigraphy; Lago Monticchio record; Bayesian method; WDS geochemical data; Discriminant function analysis (DFA). |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00039/15025/12429.pdf |
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| Howitt, Richard E.; Reynaud, Arnaud. |
| In this paper we develop a dynamic data-consistent way for estimating agricultural land use choices at a disaggregate level (district-level), using more aggregate data (regional-level). The disaggregation procedure requires two steps. The first step consists in specifying and estimating a dynamic model of land use at the regional level. In the second step, we disaggregate outcomes of the aggregate model using maximum entropy (ME). The ME disaggregation procedure is applied to a sample of California data. The sample includes 6 districts located in Central Valley and 8 possible crops, namely: Alfalfa, Cotton, Field, Grain, Melons, Tomatoes, Vegetables and Subtropical. The disaggregation procedure enables the recovery of land use at the district-level with an... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Disaggregation; Bayesian method; Maximum entropy; Land use; Production Economics; C11; C44; Q12. |
| Ano: 2002 |
URL: http://purl.umn.edu/24961 |
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