[R] lmer - BLUP prediction intervals

[Daniel Caro]

Dear all

I have a model that looks like this:

m1 <- lmer(Difference ~ 1+  (1|Examiner) + (1|Item), data=englisho.data)

I know it is not possible to estimate random effects but one can
obtain BLUPs of the conditional modes with

re1 <- ranef(m1, postVar=T)

And then dotplot(re1) for the examiner and item levels gives me a nice
prediction interval. But I would like to have the prediction interval
for the individual intercepts, not the conditional modes of the random
effects, that is, the fixed effect (overall estimated intercept) + the
conditional mode of the random effect (examiner or item level). Does
this make sense? And if so, how would I calculate this? I'd like to do
the same thing to obtain prediction intervals of individual growth
rates in longitudinal models (i.e., overall growth rate + random
effect).

Many thanks for your help,
Daniel