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Modeling count data with excess zeroes, an empirical application to traffic accidents
journal contributionposted on 18.06.2009, 15:26 by Hoong Chor Chin, Mohammed Quddus
There are many studies in social sciences, such as traffic accident analysis, in which the event counts may be characterized by a large number of zero observations. In this article, a proposed model that takes into account both the zero-count state and the nonzero- count state is used to describe the traffic accident phenomenon. The probability of the zero-count state (p) and the mean number of event counts (μ) in the non-zero-count state may depend on the covariates. Sometimes, p and μ are unrelated, while at other times, p may assume a simple function of μ. In proposing the model, different types of traffic accidents at signalized intersections in Singapore were investigated. The results demonstrate that the zero-altered probability process is an appropriate technique for modeling specific types of accidents in which the data contain many zero counts.
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