A Tutorial on Count Regression and Zero-Altered Count Models for Longitudinal Substance Use Data.

The article presents a tutorial on methods for analyzing longitudinal substance use data on the basis of hierarchical or multilevel models including Poisson, zero-inflated, and hurdle mixed models and further utilized two examples to illustrate the need for and application of longitudinal count models focusing on drinking-related consequences following an intervention for reducing problematic drinking in college students and daily drinking over the past 30 days, respectively.