Hello Fellow R

Users,I have

spent the last week trying to find a work around to this problem and I can't

seem to solve it. I simply want to plot my GEE model result with 95% confidence

bands.

I am using the geepack package to run a basic GEE model involving

nestling weights, to a Gaussian distribution, with "exchangeable" error

structure. I am examining how nestling weight varies as a function of distance

from a plot boundary.

The response variable (WEIGHT) and the explanatory

variable (DISTANCE) are both continuous. The clustering factor (MOTHER) is

entered into my model to account for similarity of nestlings from the same nest

produced by a given mother.

My simplified code is

as follows:

summary(model1<-geeglm(WEIGHT~DISTANCE,

id=MOTHER,data=df,corstr="exchangeable")))

#I've included part of the

model output

here

<Coefficients:

<

Estimate Std.err

Wald Pr(>|W|)

<(Intercept) 15.8702 0.4416

1291.8 < 2e-16 ***

<Initiationdate -0.0664

0.0157 17.9 2.4e-05

***

<

<Estimated Scale

Parameters:

<

< Estimate

Std.err

<(Intercept) 5.78

2.46

plot(df$DISTANCE,df$WEIGHT)

abline(model1)

x<-seq(min(df$DISTANCE),max(df$DISTANCE),l=1000)

y<-predict(model1,data.frame(DISTANCE=x))

Everything is fine up until this last line of code, when I get the following

error message:

"Warning message:

In predict.lm(object, newdata, se.fit, scale = 1, type = ifelse(type == :

calling predict.lm(<fake-lm-object>) ..."

This isn't a geepack problem because I get the same error message using the gee

package as well. The above simplified code is how I usually create and plot 95%

CI bands for a linear model, followed by:

matlines(x,y)

I have read through the package PDFs and searched the web and archives of

various listservs without success. Any help would be most appreciative. Seems

like there should be a simple work-around. Thank you,

Jason