
zeroinfl(count = y ~ ., x = ~1, z = ~1, data = list(), link = "logit",
dist = "poisson", method = "BFGS", trace = FALSE,
maxit = 50000, na.action = na.omit)
formula
; lowest count must be zero for
zero-inflated modelsformula
giving covariates
for the count part of the modelformula
giving covariates
for the zero-inflated part of the modellogit
(default) or probit
)"poisson"
(default) or "negbin"
"BFGS"
and
"Nelder-Mead"
are supportedTRUE
, display progress of maximizationna.omit
zeroinfl
, i.e., a list with components includingoptim
optim
is used to find
maximum likelihood estimates and to compute a Hessian matrix after
convergence.Cameron, A. Colin and Pravin K. Trevedi. 1998. Regression analysis of count data. New York: Cambridge University Press.
Long, J. Scott. 1997. Regression Models for Categorical and Limited Dependent Variables. Number 7 in Advanced Quantitative Techniques in the Social Sciences. Thousand Oaks, California: Sage.
summary.zeroinfl
, predict.zeroinfl
,
hurdle
, glm.nb
Methods are supplied for the generic functions coef
and
logLik
, for objects of class "zeroinfl"
.
data(bioChemists)
zip <- zeroinfl(count=art ~ .,
x = ~ fem + mar + kid5 + phd + ment,
z = ~ fem + mar + kid5 + phd + ment,
data=bioChemists,trace=TRUE)
summary(zip)
zinb <- zeroinfl(count=art ~ .,
x = ~ fem + mar + kid5 + phd + ment,
z = ~ fem + mar + kid5 + phd + ment,
dist="negbin",
data=bioChemists,trace=TRUE)
summary(zinb)
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