[R] glmmPQL question!
spencer.graves at pdf.com
Thu Aug 17 01:57:01 CEST 2006
I don't think there is an easy way to do that. If it were my problem,
I think I'd start by trying to the model using 'lmer' associated with
the 'lme4' package. I would then try to pass the fit to 'mcmcsamp' to
get a random sample of parameter estimates following the posterior
distribution. Then I'd convert the simulated parameters into a
distribution of predictions for the conditions of interest. While doing
this, I'd apply "quantile" of the distribution of predictions for each
set of conditions to get the desired confidence limits.
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Hope this helps.
m-krutky at northwestern.edu wrote:
> Hello Folks-
> Is there a way to create confidence bands with 'glmmPQL' ???
> I am performing a stroke study for Northwestern University in Chicago, Illinois. I am trying to
> decide a way to best plot the model which we created with the glmmPQL function in R. I would like
> to plot my actual averaged data points within 95 % confidence intervals from the model. Plotting
> the model is easy, but determining confidence bands is not.
> Here is my model:
> ratiomodel<-glmmPQL(ratio~as.factor(joint)*time, random = ~ 1 | subject, family = Gamma(link =
> I am used to seeing confidence intervals from models that increase, “flair out” in the y direction,
> at the beginning and ending time points (x values) of the simulated data. If I use 'lm' and pass
> the command 'int = "c" ' 'to create this model I can easily find and plot this type of confidence
> band for 'ratio~time'. But I need to take into account 'as.factor(joint)', and in fact I can
> produce confidence bands with 'glm' by passing in 'se.fit = TRUE', but the problem is I need to
> make subject a random variable, and take into account my ratio with the Gamma distribution.
> Is there a way to create confidence bands with 'glmmPQL' ??? ' as.factor(joint)' has 3 levels, so I
> would like to produce this linear model with three levels and confidence bands for comparison of
> the levels of 'joint'.
> Any Help at all with my problem would be greatly appreciated!!
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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