mlogit
On Mar 7, 2010, at 12:06 PM, cmc wrote:
I am trying to follow this example for multinomial logistic regression http://www.ats.ucla.edu/stat/r/dae/mlogit.htm However, I cannot get it to work properly. This is the output I get, and I get an error when I try to use the mlogit function. Any ideas as to why this happens?
mydata <- read.csv(url("http://www.ats.ucla.edu/stat/r/dae/
mlogit.csv"))
attach(mydata)
names(mydata)
[1] "brand" "female" "age"
library(mlogit)
Loading required package: Formula Loading required package: statmod
mydata[1:10,]
brand female age 1 1 0 24 2 1 0 26 3 1 0 26 4 1 1 27 5 1 1 27 6 3 1 27 7 1 0 27 8 1 0 27 9 1 1 27 10 1 0 27
mydata$brand<-as.factor(mydata$brand) mldata<-mlogit.data(mydata, varying=NULL, choice="brand", shape="wide") mldata[1:10,]
You do not get the same result as the example page, (while I do). You need to see if you have other objects with names that may be confusing the interpreter. I did not attach() mydata, which despite the UCLA's use of it is considered bad practice in R programming because of frequent obscure bugs that trip up newbies such as us. The errors do not occur when the next commands are run.
brand female age 1.1 TRUE 0 24 1.2 FALSE 0 24 1.3 FALSE 0 24 2.1 TRUE 0 26 2.2 FALSE 0 26 2.3 FALSE 0 26 3.1 TRUE 0 26 3.2 FALSE 0 26 3.3 FALSE 0 26 4.1 TRUE 1 27
mlogit.model<- mlogit(brand~1|female+age, data = mldata, reflevel="1")
Error in as.data.frame.default(data) : cannot coerce class "call" into a data.frame
summary(mlogit.model)
Error in summary(mlogit.model) : object 'mlogit.model' not found
--
David Winsemius, MD West Hartford, CT