try: library(pscl)
There's a zeroinfl for zero inflated neg. binom.
Tyler
> Date: Thu, 17 Nov 2011 17:50:46 +0100
> From: lorenzo.isella@gmail.com
> To: r-help@stat.math.ethz.ch
> Subject: [R] How to Fit Inflated Negative Binomial
>
> Dear All,
> I am trying to fit some data both as a negative binomial and a zero
> inflated binomial.
> For the first case, I have no particular problems, see the small snippet
> below
>
> library(MASS) #a basic R library
>
> set.seed(123) #to have reproducible results
>
> x4 <- rnegbin(500, mu = 5, theta = 4)
>
> #Now fit and check that we get the right parameters
>
> fd <- fitdistr(x4, "Negative Binomial")
>
> summary(fd)
>
> #and mu and theta are as expected
> #now I add artificially some zeros
>
> x5 <- sample(c(x4,rep(0,100)))
>
> However, when I artificially add some zeros (case of x5) I am unsure
> about how to proceed.
> I found some material online
>
> http://bit.ly/uPVzOT
> http://bit.ly/rXnzKi
>
> but I wonder if they are an overkill of what I am really after (a
> fitting a negative binomial with too many zeros).
> Any suggestion is really appreciated.
> Many thanks
>
> Lorenzo
>
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