On Jul 21, 2010, at 9:39 AM, Igor Blanco wrote:
Hi there,
I am trying to analyze some data using the lme package.
In my case there is a variable called Newmarker that can only take 2
values
(number 1 or number 2).
I have used the as.factor to remark this fact but an error message
appears
stating: attempt to set rownames on object with no dimensions.
Here is the code I have used:
*Dataset <- read.table("Data2.txt", header=TRUE, sep="",
na.strings="NA",
dec=".", strip.white=TRUE)
Dataset$Newmarker <- as.factor(Dataset$Newmarker)
Why do you use as.factor? It's probably already a factor. What does
str(Dataset) show?
attach(Dataset)
You do not need to do this, and it creates potential for confusion.
The data= argument will allow the column names to be accessed by the
lme() function.
lme.1 <- lme(Newmarker ~ Age, data=Dataset, random= ~1|ID)
summary(lme.1)*
If I don't use the as.factor I have no problems but I don't think
this is
the correct way to proceed... The other variables I use can have any
value.
--
David Winsemius, MD
West Hartford, CT
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