[R] zero values in LHS and RHS

zubin binabina at bellsouth.net
Wed Aug 2 05:02:28 CEST 2006


I have a data set where i need to predict hotel stays in a 3 month 
period by customer.  I have stays for each customer in the 3 month 
period and the previous 3 month period + other variables.  these stays 
contain an integer that ranges from 0 to 10.  classic poisson distribution.

my question is around zeros.  usually we could take logs on the stays 
and run an OLS model i think an enhancement would be to fit a poisson 
GLM model.  i am confused about handling of zeros.  i will have zero 
values on the RHS and potentially on the LHS.  It seems like the poisson 
GLM model can handle zeros on the LHS and RHS.   i guess my question is 
fitting a poisson GLM, are zeros allowed?  If so, how is this estimated 
with a log link function?


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