[R] Help with response CIs for lme

[Michael Kubovy]

Hi,

Can someone please offer a procedure for going from CIs produced by  
intervals.lme() to fixed-effects response CIs.

Here's a simple example:

library(mlmRev)
library(nlme)
hsb.lme <- lme(mAch ~ minrty * sector, random = ~ 1 | cses, Hsb82)
(intervals(hsb.lme))
(hsb.new <- data.frame
     minrty = rep(c('No', 'Yes'), 2),
     sector = rep(c('Public', 'Catholic'), each = 2)))
cbind(hsb.new, predict(hsb.lme, hsb.new, level = 0))

Is the following correct (I know from the previous command that the  
estimate is correct)?
cbind(hsb.new, rbind(hsb.int[[1]][1,], hsb.int[[1]][1,]+hsb.int[[1]] 
[2,], hsb.int[[1]][1,]+hsb.int[[1]][3,], hsb.int[[1]][1,]+hsb.int[[1]] 
[2,] + hsb.int[[1]][3,] + hsb.int[[1]][4,]))

If so, is there an easier way to write it?
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
USPS:     P.O.Box 400400    Charlottesville, VA 22904-4400
Parcels:    Room 102        Gilmer Hall
         McCormick Road    Charlottesville, VA 22903
Office:    B011    +1-434-982-4729
Lab:        B019    +1-434-982-4751
Fax:        +1-434-982-4766
WWW:    http://www.people.virginia.edu/~mk9y/