R-helpers:
I am getting an error when trying to fit a GEE model. Below is code
reproducing the error.
###
library(foreign)
muscatine <-
read.dta('http://www.hsph.harvard.edu/fitzmaur/ala2e/muscatine.dta')
muscatine$gender <- as.factor(muscatine$gender)
muscatine$y <- as.factor(muscatine$y)
muscatine$cage <- muscatine$age - 12
muscatine$cage2 <- muscatine$cage^2
head(muscatine); summary(muscatine)
muscatine2 <- na.omit(muscatine); summary(muscatine2) # Remove missing data
# GEE model to reproduce example in Fitzmaurice, Laird, Ware book
library(geepack)
f1 <- geeglm(y ~ gender*cage + gender*cage2, id=id, data=muscatine2,
family=binomial(link=logit),
waves=occasion, corstr='unstructured')
###
This gives me the following error
> f1 <- geeglm(y ~ gender*cage + gender*cage2, id=id, data=muscatine2,
+ family=binomial(link=logit),
+ waves=occasion, corstr='unstructured')
Error in lm.fit(zsca, qlf(pr2), offset = soffset) : NA/NaN/Inf in 'y'
In addition: Warning messages:
1: In model.response(mf, "numeric") :
using type = "numeric" with a factor response will be ignored
2: In Ops.factor(y, mu) : - not meaningful for factors
###
I would tremendously appreciate any help that could explain why I am getting
this error as I am not understanding this.
Brant
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