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Convite Seminario: Marco Rodriguez - abstract
Convite
Titulo: MODELLING SPECIES ABUNDANCE IN RELATION TO HABITAT: ALTERNATIVES
TO TRADITIONAL REGRESSION METHODS
Palestrante: Marco A. Rodr¡guez, Universite du Quebec e Trois-Rivieres
Dia 19/12/2005
Horario: 16h
Local: Bab B, Departamento de Ciencias Exatas, ESALQ/USP
Auxilio: FAPESP
Abstract
Ecologists have traditionally relied on ordinary least-square or Poisson
regressions for linking species distribution and abundance to
environmental features, but these approaches are often limited by some
restrictive assumptions. This talk presents two case studies illustrating
some of the limitations of traditional regression approaches in ecological
studies and proposes the use of alternative methods to counter these
limitations. The first study examines how the abundance (counts) of the
slimy sculpin, a fish species commonly found in North American streams,
varies in relation to habitat descriptors. The distribution of counts is
highly over-dispersed and has excess zeros, with nearly 10% of the
sampling units having zero counts. Zero-inflated negative binomial (ZINB)
regression was used to distinguish structural from sampling zeros and
separate the environmental determinants of incidence (presence/absence)
from those of abundance (number of individuals). Possible extensions of
the ZINB model incorporating random effects to account for potential
intra-group correlations in nested data are mentioned as well. The second
study illustrates the use of regression to examine the mortality of six
species of lacustrine fish in relation to habitat descriptors in the
context of survival analyses in which a portion of the data is censored.
Aproveitamos para desejar a todos
Feliz Natal e um 2006 repleto de paz, harmonia e realizacoes.
Cordiais saudacoes
Clarice
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Clarice Garcia Borges Demetrio
Departamento de Ciencias Exatas | Phone: +55 019 34294144 R:216
ESALQ/USP | Fax: +55 019 34294346
Caixa Postal 9 | http://ce.esalq.usp.br/
13418-900 PIRACICABA, SP |
BRASIL | clarice@carpa.ciagri.usp.br
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