Spatial modeling of data with excessive zeros applied to reindeer pellet-group counts


Autoria(s): Youngjo, Lee; Alam, Moudud; Noh, Maengseok; Rönnegård, Lars; Skarin, Anna
Data(s)

2016

Resumo

We analyze a real data set pertaining to reindeer fecal pellet-group counts obtained from a survey conducted in a forest area in northern Sweden. In the data set, over 70% of counts are zeros, and there is high spatial correlation. We use conditionally autoregressive random effects for modeling of spatial correlation in a Poisson generalized linear mixed model (GLMM), quasi-Poisson hierarchical generalized linear model (HGLM), zero-inflated Poisson (ZIP), and hurdle models. The quasi-Poisson HGLM allows for both under- and overdispersion with excessive zeros, while the ZIP and hurdle models allow only for overdispersion. In analyzing the real data set, we see that the quasi-Poisson HGLMs can perform better than the other commonly used models, for example, ordinary Poisson HGLMs, spatial ZIP, and spatial hurdle models, and that the underdispersed Poisson HGLMs with spatial correlation fit the reindeer data best. We develop R codes for fitting these models using a unified algorithm for the HGLMs. Spatial count response with an extremely high proportion of zeros, and underdispersion can be successfully modeled using the quasi-Poisson HGLM with spatial random effects.

Formato

application/pdf

Identificador

http://urn.kb.se/resolve?urn=urn:nbn:se:du-23163

doi:10.1002/ece3.2449

ISI:000385626100026

Idioma(s)

eng

Publicador

Högskolan Dalarna, Statistik

Högskolan Dalarna, Statistik

Seoul National University

Pukyong National University, Korea

Swedish University of Agricultural Science, Uppsala

Wiley

Relação

Ecology and Evolution, 2045-7758, 2016, 6:19, s. 7047-7056

Direitos

info:eu-repo/semantics/openAccess

Palavras-Chave #excessive zeors #habitat preference #hierarchical generalized linear model #pellet-group counts #Poisson model #spatial correlation #Probability Theory and Statistics #Sannolikhetsteori och statistik
Tipo

Article in journal

info:eu-repo/semantics/article

text