ZIGP-package {ZIGP} | R Documentation |
Adapts ZIGP models by Maximum Likelihood estimation. Regression is allowed not only on the mean but also on overdispersion and zero-inflation level. Therefore, three design matrices are used.
Package: | ZIGP |
Type: | Package |
Version: | 1.1 |
Date: | 2007-02-01 |
License: | GPL (v.2 or later) |
Distribution functions in R notation are 'dzigp', 'pzigp', 'qzigp', 'rzigp'.
The most important function is 'wald.test'. This function can be fed with design matrices for the mean, overdispersion and zero-inflation level. It returns an summary-like overview of the covariates together with significance statistics referring to the Wald test. It can be used for the sequential elimination of non-significant effects.
Other useful functions are 'loglikelihood.zigp', which evaluates the loglikelihood function on the given parameter value. Scores can be calculated using 'gradient', the Fisher Information matrix using 'FM'.
Vinzenz Erhardt
Maintainer: Vinzenz Erhardt <erhardt@ma.tum.de>
Masterthesis in German: Erhardt, Vinzenz. Verallgemeinerte Poisson und Nullenueberschuss- Regressionsmodelle mit regressiertem Erwartungswert, Dispersions- und Nullenüberschuß-Parameter und eine Anwendung zur Patentmodellierung. ("http://www-m4.ma.tum.de/Diplarb/"), 2006