[R] logistic regression or not?
array chip
arrayprofile at yahoo.com
Tue Dec 21 01:40:01 CET 2010
Hi, I have a dataset where the response for each person on one of the 2
treatments was a proportion (percentage of certain number of markers being
positive), I also have the number of positive & negative markers available for
each person. what is the best way to analyze this kind of data?
I can think of analyzing this data using glm() with the attached dataset:
test<-read.table('test.txt',sep='\t')
fit<-glm(cbind(positive,total-positive)~treatment,test,family=binomial)
summary(fit)
anova(fit, test='Chisq')
First, is this still called logistic regression or something else? I thought
with logistic regression, the response variable is a binary factor?
Second, then summary(fit) and anova(fit, test='Chisq') gave me different p
values, why is that? which one should I use?
Third, is there an equivalent model where I can use variable "percentage"
instead of "positive" & "total"?
Finally, what is the best way to analyze this kind of dataset where it's almost
the same as ANOVA except that the response variable is a proportion (or success
and failure)?
Thanks
John
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