zero truncated poisson regression - R-help

Mon, Aug 1, 2011 12:10 AM #

On Sun, 31 Jul 2011, Iasonas Lamprianou wrote:

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)

________________________________
From: Mitchell Maltenfort <mmalten at gmail.com>
To: Iasonas Lamprianou <lamprianou at yahoo.com>; "r-help at r-project.org" <r-help at 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 <lamprianou at 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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--
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Iasonas Lamprianou

Mon, Aug 1, 2011 1:37 AM #

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Achim Zeileis

Mon, Aug 1, 2011 4:14 PM #

On Mon, 1 Aug 2011, Iasonas Lamprianou wrote:

The package still needs some proper documentation and some cleaning up 
which is why it is not yet on CRAN.

The code, however, is well tested because it is exactly the code 
underlying the hurdle() function in "pscl". Hence, the "zerotrunc" objects 
are rather similar in many respect to "hurdle" objects. Starting from the 
JSS paper you should hopefully be able to find your way.
Z

________________________________
From: Achim Zeileis <Achim.Zeileis at uibk.ac.at>
To: Iasonas Lamprianou <lamprianou at yahoo.com>
Cc: Mitchell Maltenfort <mmalten at gmail.com>; "r-help at r-project.org" <r-help at r-project.org>
Sent: Monday, 1 August 2011, 10:10
Subject: Re: [R] zero truncated poisson regression

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 <mmalten at gmail.com>
To: Iasonas Lamprianou <lamprianou at yahoo.com>; "r-help at r-project.org" <r-help at 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 <lamprianou at 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

??? [[alternative HTML version deleted]]

--
Sent from my mobile device

Due to the recession, requests for instant gratification will be
deferred until arrears in scheduled gratification have been satisfied.

??? [[alternative HTML version deleted]]