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Spatial modeling of data with excessive zeros applied to reindeer pellet-group counts
Seoul National University.
Dalarna University, School of Technology and Business Studies, Statistics.ORCID iD: 0000-0002-3183-3756
Pukyong National University, Korea.
Dalarna University, School of Technology and Business Studies, Statistics.ORCID iD: 0000-0002-1057-5401
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2016 (English)In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, 7047-7056 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Wiley, 2016. Vol. 6, 7047-7056 p.
Keyword [en]
excessive zeors, habitat preference, hierarchical generalized linear model, pellet-group counts, Poisson model, spatial correlation
National Category
Probability Theory and Statistics
Research subject
Complex Systems – Microdata Analysis
URN: urn:nbn:se:du-23163DOI: 10.1002/ece3.2449OAI: diva2:972533
Available from: 2016-09-21 Created: 2016-09-21 Last updated: 2016-10-07Bibliographically approved

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Alam, MoududRönnegård, Lars
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