[R] Negative Binomial Predictions

Donald Catanzaro, PhD dgcatanzaro at gmail.com
Wed Oct 1 18:17:39 CEST 2008

Good Day All,

I have a negative binomial model which I have developed using the MASS 
library.  I now would like to develop some predictions from it. 

Running the predict.glm (stats library) using type="response" gives me a 
non-integer value which was rather puzzling.  I would like to confirm 
that this is actually the mean predicted value of the probability mass 
function as opposed to the most likely value.  I am afraid that reading 
the help file for predict.glm either does not state this or I don't 
understand what it states (which of course could always be the case)

Given that this is a negative binomial model, the mean is often times to 
the right of the most likely value, so I'd like to ask how one would go 
about predicting the most likely value. 

Thanks in advance !



Don Catanzaro, PhD                  Landscape Ecologist
dgcatanzaro at gmail.com               16144 Sigmond Lane
479-751-3616                        Lowell, AR 72745

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