Are you referring to the zeroinfl() function in the countreg package? If so, I think
predict(fm_zinb2, type = "zero", newdata = some.new.data) will give you pi for each combination of covariate values that you provide in some.new.data where pi is the probability to observe a zero from the point mass component. As to your second question, I'm not sure that's possible, for any *particular, individual* subject. Others will undoubtedly know better than I. --Chris Ryan Sorkin, John wrote: > I am running a zero inflated regression using the zeroinfl function similar > to the model below: > > fm_zinb2 <- zeroinfl(art ~ . | ., data = bioChemists, dist = "poisson") > summary(fm_zinb2) > > I have three questions: > > 1) How can I obtain a value for the parameter pie, which is the fraction of > the population that is in the zero inflated model vs the fraction in the > count model? > > 2) For any particular subject, how can I determine if the subject is in the > portion of the population that contributes a zero count because the subject > is in the group of subjects who have structural zero responses vs. the > subject being in the portion of the population who can contribute a zero or a > non-zero response? > > 3) zero inflated models can be solved using closed form solutions, or using > iterative methods. Which method is used by fm_zinb2? > > Thank you, > John > > John David Sorkin M.D., Ph.D. > Professor of Medicine, University of Maryland School of Medicine; > > Associate Director for Biostatistics and Informatics, Baltimore VA Medical > Center Geriatrics Research, Education, and Clinical Center; > > PI Biostatistics and Informatics Core, University of Maryland School of > Medicine Claude D. Pepper Older Americans Independence Center; > > Senior Statistician University of Maryland Center for Vascular Research; > > Division of Gerontology and Paliative Care, > 10 North Greene Street > GRECC (BT/18/GR) > Baltimore, MD 21201-1524 > Cell phone 443-418-5382 > > > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
