MIXZIP 1.0 for Mixed-effects Zero-Inflated Poisson (ZIP) Regression
mixzip1.exe (816 KB)
MIXZIP provides the maximum marginal likelihood
estimates of mixed-effects Zero-Inflated Poisson (ZIP) regression
models. In the context of a regression model, the ZIP model allows
one to estimate one set of regression coefficients for use or non-use
of services and a separate set of regression coefficients for the
amount of services used, conditional on their use. The mixed-effects
case is a generalization of the ZIP model for analysis of longitudinal
and / or clustered service utilization data where the data within
clusters are assumed to be dependent. MIXZIP uses marginal maximum
likelihood estimation, utilizing a Newton-Raphson iterative solution.
Currently, the program allows for single but separate random effects
for both logistic and Poisson components of the model.