Dr. Stevens,
I've double-checked my variable lengths. All of my variables
(Total.vines, Site, Species, and DBH) came in at 549. I did correct
one problem in the data entry that had escaped my previous notice:
somehow the undergrad who entered all the data managed to make the
Acer
On Thu, 16 Aug 2007, James R. Milks wrote:
Dr. Stevens,
I've double-checked my variable lengths. All of my variables
(Total.vines, Site, Species, and DBH) came in at 549. I did correct
one problem in the data entry that had escaped my previous notice:
somehow the undergrad who entered all
No, zeroinfl() in pscl did not give me any errors when I ran the
model. So there may be a bug in zicounts. Only problem now is how
to interpret the zeroinfl model. Am I correct in my understanding
that zeroinfl runs both the poisson and binomial models without
interactions? I'm
Hi Jim,
Two thoughts come to me, unencumbered by the thought process or
knowledge of zicounts:
1. Is Poisson really NOT appropriate? (do you have to use zicounts?)
2. Are you 110% certain that all variables are the same length? Would
NA's interfere?
Cheers,
Hank
On Aug 13, 2007, at 5:10 PM,
I have data on number of vines per tree for ~550 trees. Over half of
the trees did not have any vines and the data is fairly skewed
(median = 0, mean = 1.158, 3rd qu. = 1.000). I am attempting to
investigate whether plot location (four sites), species (I'm using
only the four most common
