background: the aim of this study was to assess the associations between nutrition and dental caries in permanent dentition among schoolchildren. methods: a cross-sectional survey was undertaken on 698 schoolchildren aged 10 to 12 yr from a random sample of primary schools in kermanshah, western iran, in 2014. the study was based on the data obtained from the questionnaire containing informatio...

Count data sometimes exhibit a greater proportion of zero counts than is consistent with the data having been generated by a simple Poisson or negative binomial process. For example, a preponderance of zero counts have been observed in data that record the number of automobile accidents per driver, the number of criminal acts per person, the number of derogatory credit reports per person, the n...

Abstract Zero-inflated and hurdle models are widely applied to count data possessing excess zeros, where they can simultaneously model the process from how zeros were generated potentially help mitigate effects of overdispersion relative assumed distribution. Which use depends on generated: zero-inflated add an additional probability mass zero, while two-part comprised a degenerate distribution...

Count data with excess zeros are common in social science research and can be considered as a special case of mixture structured data. We exploit the flexibility of the Bayesian analytic approach to model the mixture data structure inherent in zero-inflated count data by using the zero-inflated Poisson (ZIP) model. We discuss the importance of modelling excess-zero count data in social sciences...

In a variety of research domains, data are generated as a consequence of the count process and may possess an ‘excess’ of zeros. There have been many attempts to analyse such data using different statistical methods, including the zero-inflated Poisson (ZiP) and zero-inflated binomial (ZiB) models. The interpretation of these models is however problematic if the covariates considered for the no...

Zero-inflated data abound in ecological studies as well as in other scientific and quantitative fields. Nonparametric regression with zero-inflated response may be studied via the Zero-Inflated Generalized Additive Model (ZIGAM). ZIGAM assumes that the response variable follows a probabilistic mixture distribution of a zero atom and a regular component whose distribution belongs to some 1-param...

This paper presents a quasi-conditional likelihood method for the consistent estimation of both continuous and count data models with excess zeros and unobserved individual heterogeneity when the true data generating process is unknown. Monte Carlo simulation studies show that our zero-inflated quasi-conditional maximum likelihood (ZI-QCML) estimator outperforms other methods and is robust to d...