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Registros recuperados: 5
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A Bayesian state-space model to estimate population biomass with catch and limited survey data: application to the thornback ray (Raja clavata) in the Bay of Biscay ArchiMer
Marandel, Florianne; Lorance, Pascal; Trenkel, Verena M..
The thornback ray (Raja clavata) in the Bay of Biscay is presumed to have declined during the 20th Century. To evaluate this decline and estimate biomass trajectories, a hypothetical catch time series was created for the period 1903-2013. A Bayesian state-space biomass production model with a Schaefer production function was fitted to the hypothetical catch time series and to a shorter research vessel Catch Per Unit Eeffort (CPUE) time series (1973-2013, with missing years). A censored likelihood made it possible to obtain biomass estimates without a CPUE time series or only with an estimate of biomass depletion. A simulation-estimation approach showed a high sensitivity of results to the prior for the intrinsic growth rate. The model provided biomass...
Tipo: Text Palavras-chave: Population dynamics; Stock assessment; Data poor; Censored data; Bayes; Thornback ray; State-space model.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00359/47032/46947.pdf
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Censored catch data in fisheries stock assessment ArchiMer
Hammond, T; Trenkel, Verena.
Landings statistics can be lower than true catches because many fish are discarded or landed illegally. Since many discards do not survive, treating landings as true catches can lead to biased stock assessments. This paper proposes treating catch as censored by bounding it below by the landings, L, and above by cL (for scalar c > 1), We demonstrate the approach with a simulation study, using a Schaefer surplus production model. Parameters were estimated in a Bayesian framework with BUGS software using two sets of priors. Both the traditional true-catch method and a survey-and-effort method (which was landings free) performed worse on average than the censored approach, as measured by the Bayes risk associated with estimates of maximum sustainable yield...
Tipo: Text Palavras-chave: Stock assessment; Misreporting; Discarding; Censored data.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-641.pdf
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Genomic prediction for additive and dominance effects of censored traits in pigs. Repositório Alice
SANTOS, V. S.; MARTINS FILHO, S.; RESENDE, M. D. V. de; AZEVEDO, C. F.; LOPES, P. S.; GUIMARÃES, S. E. F.; SILVA, F. F..
Age at the time of slaughter is a commonly used trait in animal breeding programs. Since studying this trait involves incomplete observations (censoring), analysis can be performed using survival models or modified linear models, for example, by sampling censored data from truncated normal distributions. For genomic selection, the greatest genetic gains can be achieved by including non-additive genetic effects like dominance. Thus, censored traits with effects on both survival models have not yet been studied under a genomic selection approach. We aimed to predict genomic values using the Cox model with dominance effects and compare these results with the linear model with and without censoring. Linear models were fitted via the maximum likelihood method....
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: GBLUP; Modelo mixto; Censored data; Mixed model; Survival models; Porco; Suíno; Swine; Animal breeding.
Ano: 2016 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1072712
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OLS and Tobit Estimates: When is Substitution Defensible Operationally? AgEcon
Wilson, Clevo; Tisdell, Clement A..
Field data are used to illustrate that, other things constant, regression results using Ordinary Least Squares (OLS) converge to Tobit estimates as the number of zeros in the regressand decrease. Tobit estimates are theoretically superior to OLS estimates when using censored data. However, if little difference exists between OLS and Tobit estimates, OLS may be operationally acceptable. OLS may even be optimal in a bounded rationality sense because the extra cost of using Tobit analysis may be less than the extra benefits from a very slight increase in accuracy.
Tipo: Working or Discussion Paper Palavras-chave: Bounded rationality; Censored data; Ordinary Least Squares; Tobit; Regressand; Willingness to pay studies.; Public Economics.
Ano: 2002 URL: http://purl.umn.edu/90519
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Stings in the tails: Detecting and dealing with censored data AgEcon
Conroy, Ronan M..
Variables often show evidence of clustering at extreme values and of graininess, that is, of a limited number of distinct values. Scores on two subscales of a quality-of-life measure, traditionally analyzed with OLS regression or ANOVA models, provide examples. Ignoring or failing to detect such features of the data will result in poor estimates of effect size.
Tipo: Journal Article Palavras-chave: Censored data; Diagnostic plots; Intreg; Research Methods/ Statistical Methods.
Ano: 2005 URL: http://purl.umn.edu/117528
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