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Modeling zero‐inflated count data when exposure varies: With an application to tumor counts
Author(s) -
Baetschmann Gregori,
Winkelmann Rainer
Publication year - 2013
Publication title -
biometrical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 63
eISSN - 1521-4036
pISSN - 0323-3847
DOI - 10.1002/bimj.201200021
Subject(s) - count data , statistics , zero (linguistics) , zero inflated model , poisson distribution , weibull distribution , mathematics , logit , overdispersion , poisson regression , econometrics , medicine , population , philosophy , linguistics , environmental health
This paper is concerned with the analysis of zero‐inflated count data when time of exposure varies. It proposes a modified zero‐inflated count data model where the probability of an extra zero is derived from an underlying duration model with Weibull hazard rate. The new model is compared to the standard Poisson model with logit zero inflation in an application to the effect of treatment with thiotepa on the number of new bladder tumors.