I've been working on a multinomial logit model, trying to predict
vegetation types as a function of total phosphorus. Previous responses to
my postings have pointed me to the mlogit package. I'm now trying to work
examples and my data using this package.
data("Fishing", package = "mlogit")
Fish <- mlogit.data(Fishing, varying = c(4:11), shape = "wide", choice =
"mode")
both of those lines work, as expected.
However;
summary(mlogit(mode ~ pr + ca -1, data = Fish))
Call:
Error in deparse(obj...@call) :
trying to get slot "call" from an object (class "mlogit") that is not an
S4 object
Using my data I've done the following:
xx <- fwc # copies and protects original data.frame
xx$VegType <- as.factor(xx$VegType)
xx.dat <- mlogit.data(xx, varying = "NULL", choice = "VegType", shape =
"wide")
xx.mlogit <- mlogit(VegType ~ TP, data = xx.dat,, reflevel = "1")
Error in relevel.factor(attr(mf, "index")[["alt"]], reflevel) :
'ref' must be an existing level
Can someone explain why these errors are occuring and what to do about
them?
Thanks
Using R 2.10.1, Windows XP
Steve Friedman Ph. D.
Spatial Statistical Analyst
Everglades and Dry Tortugas National Park
950 N Krome Ave (3rd Floor)
Homestead, Florida 33034
steve_fried...@nps.gov
Office (305) 224 - 4282
Fax (305) 224 - 4147
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
