Dear R users, I want to apply zero inflated models with continuous and categorical variables and I used pscl package from R and the zeroinf() function. My question are the follow: a) The value of fitted.values is mu or (1-p)*mu? where p is the probability of zero came form a zero point mass b) If mu is zero, how do i know if it is a zero from the zero point mass or from the count process? Thank you so much in advance. Filipa J. -- View this message in context: http://r.789695.n4.nabble.com/Zero-inflated-Models-pscl-package-tp4642689.html Sent from the R help mailing list archive at Nabble.com.
Zero inflated Models- pscl package
2 messages · Filipa J., Achim Zeileis
On Mon, 10 Sep 2012, Filipa J. wrote:
Dear R users, I want to apply zero inflated models with continuous and categorical variables and I used pscl package from R and the zeroinf() function. My question are the follow: a) The value of fitted.values is mu or (1-p)*mu? where p is the probability of zero came form a zero point mass
See vignette("countreg", package = "pscl"), especially Appendix C.
The default predict(..., type = "response") and fitted(...) both compute
the expected value Equation (8). This corresponds to your (1-p)*mu but
uses a different notation.
b) If mu is zero, how do i know if it is a zero from the zero point mass or from the count process?
You can inspect all component: Your "mu" ("exp(x'b)" in the notation of
the paper) can be computed with predict(..., type = "count") and "p" ("pi"
in the paper) with predict(..., type = "zero").
Best,
Z