Type of Tool  RFunction 
Title  Zero Inflated Poisson R 
Programmer/Email  Naji Lu 
Contributing Site  Rochester 
Description 
The R code fits the ZeroInflated Poisson (ZIP) like loglinear model to prepost longitudinal data with missing value at postassessment, using a set of weighted generalized estimating equations to provide distributionfree inference about model parameters. The output includes estimates and standard errors for both the logistic and Poisson regression parts of the ZIP like model. An introduction to use the ZeroInflated Poisson R Program 
Example  Example code 
Classification Graph Type 

References 
Dobbie, M.J. and Welsh, A.H. Modeling correlated zeroinflated count data. Australian & New Zealand Journal of Statistics, 2001, 43, 431444. Kowalski, J. and Tu, X.M. Modern Applied UStatistics, Wiley, New York, 2007. Lambert, D. Zeroinflated Poisson regression, with an application to defects in manufacturing. Technometrics, 1992, 34, 114 McCullagh, P. and Nelder, J.A. Generalized Linear Models, 2nd.ed., Chapman and Hall, London. 1989. 
Datasets 

Data 

Software Program  R 
Software  R 
Macro Parameters 
The required parameters (n, noc): 1. n=Number of subjects 2. noc=Number of covariates 
RCode  Attachment  Rochester_ZIP_R Function 
RCode 

SASCode  Attachment 

SASCode 

StataCode  Attachment 

StataCode 

Other Code  Attachment 

Other Code 

Called Data Manipulation 

Called Tool/Utility 

Called Checking Macro 

Called Other 

CreationDate 

RevisionDate  December 20, 2010 
Example Code  R Example Code 
Example Output  R Example Output 
SAS Examples 

SAS_Example_Code 

SAS_Example_Output 

R Examples 

R_Example_Code  Rochester_ZIP_R Example Code 
R_Example_Output  Rochester_ZIP_R Example Output 
Stats Examples 

Special Features 

Special Features Attached 

Special Features Text 

Notes1Legend  Section with calls to needed macros 
Notes1 

Notes2Legend  Macro call with fully specified parameters 
Notes2 

Notes3Legend  Section with definitions of global macro parameters 
Notes3 

Notes4Legend  Section with definitions of local macro variables 
Notes4 

See Also 

Checklists 

Stat Tools Disclaimer 
This R function is developed by Dr. Naiji Lu , along with other members in the Department of Biostatistics and Computational Biology at the University of Rochester under the auspice of the CTSI BERD with the intent to facilitate data analyses and reporting in clinical and related research. It is copyrighted by Dr. Naiji Lu on December 20, 2010 and distributed for free public access The development of this macro was supported in part by an NIH grant R21/R33 DA027521. 
Discliamer 
The views expressed within CTSpedia are those of the author and must not be taken to represent policy or guidance on the behalf of any organization or institution with which the author is affiliated. 
Permission 
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF ERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT OLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 
Reference Image 
