title: Zero-inflated regression models for radiation-induced chromosome aberration data: A comparative study.
abstract: Within the field of cytogenetic biodosimetry, Poisson regression is the classical approach for modeling the number of chromosome aberrations as a function of radiation dose. However, it is common to find data that exhibit overdispersion. In practice, the assumption of equidispersion may be violated due to unobserved heterogeneity in the cell population, which will render the variance of observed aberration counts larger than their mean, and/or the frequency of zero counts greater than expected for the Poisson distribution. This phenomenon is observable for both full- and partial-body exposure, but more pronounced for the latter. In this work, different methodologies for analyzing cytogenetic chromosomal aberrations datasets are compared, with special focus on zero-inflated Poisson and zero-inflated negative binomial models. A score test for testing for zero inflation in Poisson regression models under the identity link is also developed.
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, UK.
authors.forename: María
authors.initials: M
authors.lastname: Oliveira
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, UK.
authors.forename: Jochen
authors.initials: J
authors.lastname: Einbeck
authors.affiliation: Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK.|Departament de Matematiques, Universitat Autonoma de Barcelona, Bellaterra (Barcelona) 08193, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Higueras
authors.affiliation: Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ainsbury
authors.affiliation: Departament de Matematiques, Universitat Autonoma de Barcelona, Bellaterra (Barcelona) 08193, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Puig
authors.affiliation: Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK.|Department of Radiotherapy & Radio-Oncology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Rothkamm
mesh_terms: D001699:Biometry; D002869:Chromosome Aberrations / Q000528:radiation effects; D020732:Cytogenetic Analysis; D006801:Humans; D015233:Models, Statistical; D016012:Poisson Distribution; D011874:Radiometry; D012044:Regression Analysis; D014916:Whole-Body Irradiation
keywords: Biological dosimetry; Chromosome aberrations; Count data; Overdispersion; Score tests; Zero inflation