[Limdep Nlogit List] Endogenous Stratification - Poisson Count Data Model

[Peter Edwards]

Hello All

I am attempting to conduct a Poisson regression on a data set for an On-Site 
Travel cost model.

The on-site nature of the sampling means that the data is truncated at zero. 
There is also an issue of oversampling of more frequent users of the 
resource (some persons visit the site only once over the period, others 
more).

I would like to know if there is a command in the command builder section of 
the Poisson Model for dealing with Endogenous Stratification.  I have been 
searching the reference manuals but I am not sure if this issue is refered 
to by another name.
I'm unsure if this should be addressed by Sample Selection models, ir Zero 
inflated poisson (ZIP) models.

Or do we have to write the code for the likelihood functions separately?

Thanks in advance for the help!

PETER

++++++++++++++++++++++++++++++++
Peter E.T. Edwards
PhD. Candidate
University of Delaware
Graduate College of Marine and Earth Studies
Room 312 Robinson Hall
Newark, DE 19716
http://www.ocean.udel.edu/