[R] Structural equation models (SEM) for count data / poisson distribution

[Stella Copeland]

Dear R community,

I am constructing structural equation models in R and I have tried both 
the sem and lavaan packages. I have count data (numbers of plants in 
this case) that I would like to use as an endogenous variable. The 
poisson distribution seems appropriate for these data, but I can't seem 
to figure out how best to handle this within either package, lavaan or 
sem, though I have noticed that both packages are adding lots of 
options/capability to their core sem functions, so perhaps I have missed 
something.

Could someone recommend a reasonable approach for handling count data 
with SEM in R, in either lavaan or sem?

Thanks in advance for comments and suggestions,
Stella

-- 
Stella Copeland
PhD Candidate
Environmental Science & Policy
UC Davis