[R] Plotting GEE confidence bands using "predict"

[Shige Song]

Hi Jason,

I would go for Zelig package to get simulated values and confidence
intervals. It can handle gee model.

Shige

On Mon, Oct 17, 2011 at 9:38 AM, JASON M. HILL <jmh656 at psu.edu> wrote:
> 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
>
>
>
>
>
>
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>
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