bootstrap() function used in lmer object

Question

I have a question pertaining to the R presentation by José A. Sánchez-Espigares and Jordi Ocaña entitled "An R implementation of bootstrap procedures for mixed models".

See: http://www.r-project.org/conferences/useR-2009/slides/SanchezEspigares+Ocana.pdf

On slide 22 on the examples they use the function bootstrap() (in the slide it is: sleep.boot=bootstrap(model,B=1000) ).

The only package they reference is lme4 but that package does not contain the bootstrap() function and I get:

Error: could not find function "bootstrap"

Does anybody know what package they are using here?

Answer 1

I am 99% sure that lme4 never had a bootstrap() function, and that it in fact came from code written by the presenters (I have looked for that code on-line before but have never found it). The built-in bootMer function tries to do most of what this presentation describes, but doesn't do everything (e.g. it doesn't include an implementation of a Wild bootstrap).

If you want to use bootMer without specifying a function FUN, you might take a look at confint(.,method="boot") ... it looks like the summary function that the authors used might have been something like

function(x) c(fixef(x),getME(x,"theta"),sigmaREML=sigma(x))