title: Zero tolerance ecology: improving ecological inference by modelling the source of zero observations.
abstract: A common feature of ecological data sets is their tendency to contain many zero values. Statistical inference based on such data are likely to be inefficient or wrong unless careful thought is given to how these zeros arose and how best to model them. In this paper, we propose a framework for understanding how zero-inflated data sets originate and deciding how best to model them. We define and classify the different kinds of zeros that occur in ecological data and describe how they arise: either from 'true zero' or 'false zero' observations. After reviewing recent developments in modelling zero-inflated data sets, we use practical examples to demonstrate how failing to account for the source of zero inflation can reduce our ability to detect relationships in ecological data and at worst lead to incorrect inference. The adoption of methods that explicitly model the sources of zero observations will sharpen insights and improve the robustness of ecological analyses.
authors.affiliation: The Ecology Centre, School of Life Sciences, The University of Queensland, Brisbane, Qld 4072, Australia Environmental Science, School of Botany, University of Melbourne, Vic. 3010, Australia School of Geography, Planning and Architecture, The University of Queensland, Brisbane, Qld 4072, Australia CSIRO Mathematical and Information Sciences, Cleveland, Qld, Australia School of Earth and Environmental Sciences, University of Adelaide, North Terrace, SA 5005, Australia School of Mathematical Sciences, Queensland University of Technology, Brisbane, Qld 4001, Australia School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, USA.
authors.forename: Tara G
authors.initials: TG
authors.lastname: Martin
authors.forename: Brendan A
authors.initials: BA
authors.lastname: Wintle
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Rhodes
authors.forename: Petra M
authors.initials: PM
authors.lastname: Kuhnert
authors.forename: Scott A
authors.initials: SA
authors.lastname: Field
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Low-Choy
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tyre
authors.forename: Hugh P
authors.initials: HP
authors.lastname: Possingham