pscl is an R package providing classes, methods and test data for
Bayesian analysis of roll call data and other binary, item-response type data (e.g., from surveys or educational testing).
elementary Bayesian statistics
maximum likelihood estimation of zero-inflated and hurdle models for count data
utility functions
The Political Science Computational Laboratory was the name of Simon Jackman's research group at Stanford University's Department of Political Science (2002-2014), where this package was first developed.
The hurdle and count data models were extensively re-written and updated by Achim Zeileis and Christian Kleiber.
Most users should use latest stable release of the package, which can be installed from CRAN by running
install.packages("pscl")The development version can be installed directly from GitHub by running
install.packages("devtools") ## if not already installed
library(devtools)
install_github("atahk/pscl")