On Sun, 31 Jul 2011, Iasonas Lamprianou wrote:
Thanks
Pscl seems to be a sensible option.
I have the counts variable with the name "N". This variable can only
take values bigger than zero!
I have two explanatory variables with the names "type" and "diam"
but when I run
hpm <- hurdle(n ~ type+diam, data = an, dist = "poisson")
I get the message "invalid dependent variable, minimum count is not
zero". Well, I know that N>0, that is why want to run a zero-truncated
model. But I must be missing something...and the manual does not seem to
help a lot...
Can anyone help please?
As previously pointed out by others on this list: hurdle() is not what you
are looking for (although it is related to what you want to do). The
hurdle() model is a two-part model consisting of a zero-truncated count
part and a binary part for modeling N=0 vs N>0. See also
vignette("countreg", package = "pscl") for details.
As you don't need the binary hurdle part, you cannot use hurdle()
directly.
This is why the package "countreg" on R-Forge provides the function
zerotrunc() which essentially does the same thing as the count part in
hurdle().
install.packages("countreg", repos = "http://R-Forge.R-project.org";)
library("countreg")
m <- zerotrunc(n ~ type + diam, data = an, dist = "poisson")
summary(m)
?
Dr. Iasonas Lamprianou
Department of Social and Political Sciences
University of Cyprus
________________________________
From: Mitchell Maltenfort <mmal...@gmail.com>
To: Iasonas Lamprianou <lampria...@yahoo.com>; "r-help@r-project.org"
<r-help@r-project.org>
Sent: Sunday, 31 July 2011, 20:45
Subject: Re: [R] zero truncated poisson regression
Pscl package.
On 7/31/11, Iasonas Lamprianou <lampria...@yahoo.com> wrote:
Dear friends,
does anyone know how I can run a zero truncated poisson regression using R
(or even SPSS)?
Dr. Iasonas Lamprianou
Department of Social and Political Sciences
University of Cyprus
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