In this study, two-state Markov switching count data models are proposed as an alternative to zero-inflated models, in order to account for preponderance of zeros typically observed in accident frequency data. Similar to zero-inflated models, two-state Markov switching models assume an existence of two states of roadway safety. One of the states is a zero-accident state, which is safe. The othe...

Abstract The logistic regression model has become a standard tool to investigate the relationship between binary outcome and set of potential predictors. When analyzing data, it often arises, however, that observed proportion zeros is greater than expected under postulated model. Zero-inflated binomial (ZIB) models have been developed fit data contain too many zeros. Maximum likelihood estimato...

OBJECTIVES In assisted reproductive technology, it is important to choose high quality embryos for embryo transfer. The aim of the present study was to determine the grade A embryo count and factors related to it in infertile women. MATERIALS AND METHODS This historical cohort study included 996 infertile women. The main outcome was the number of grade A embryos. Zero-Inflated Poisson (ZIP) r...

BACKGROUND Alcohol consumption is commonly used as a primary outcome in randomized alcohol treatment studies. The distribution of alcohol consumption is highly skewed, particularly in subjects with alcohol dependence. METHODS In this paper, we will consider the use of count models for outcomes in a randomized clinical trial setting. These include the Poisson, over-dispersed Poisson, negative ...

    Background: Use of methamphetamine (MA) and other stimulants has increased steadily over the past 10 years. Risk factor evaluation to reduce the problem in the community is one solution to protect people from addiction. This study aimed at using Bayesian zero- inflated Poisson (ZIP) model to investigate the relationship between the number of using crystal meth and some demogr...

Using a sample of male and female workers from the 1992 Employment in Britain survey we estimate a generalised grouped zero-inflated Poisson regression model of employees’ selfreported lateness. Reflecting theoretical predictions from both psychology and economics, lateness is modelled as a function of incentives, the monitoring of and sanctions for lateness within the workplace, job satisfacti...

background: stroke is a prevalent cause of disability in adults. the fall is the most common balance and motor impairments, which affects the quality of life in stroke patients. this study aims to employ random effects hurdle model for evaluating the balance improvement in stroke patients under the occupational therapy. methods: in this longitudinal study with repeated measurement during one ye...

To account for the preponderance of zero counts and simultaneous correlation of observations, a class of zero-inflated Poisson mixed regression models is applicable for accommodating the within-cluster dependence. In this paper, a score test for zero-inflation is developed for assessing correlated count data with excess zeros. The sampling distribution and the power of the test statistic are ev...