[R] qu: predict with lmer (lme4) or other ways to get classification accuracy

[T. Florian Jaeger]

Hi,

I am using lmer (from the package lme4) to predict a binary response
variable (REL) from a bunch of fixed effects and two random effects
(Speaker_ID and NPhead_lemma):

fit <- lmer(REL ~
	SPEAKER_GENDER +
	log(SPEECHRATE) +
	SQSPEECHRATE +
        .....
        + (1|Speaker_ID) + (1|NPhead_lemma),
	family="binomial",
	data=data.lmer,
	method="Laplace", model=T, x=T)

I would like to get classification accuracies for the derived model,
or even do some evaluation (cross-validation), but I cannot find a way
to get to the predicted values. As far as I can tell no predict method
has been implemented for lmer, right? I also was trying to figure out
whether lmer stores the predicted values somewhere (I read the
documentation and implementation summary,
/library/lme4/doc/Implementation.pdf).

Many thanks for your help and my apologies if I overlooked something
really simple.

Florian

--
T. Florian Jaeger
Ph.D. student
Linguistics Department,
P: +1 (650) 725 2323
F: +1 (650) 723 5666
U: http://www.stanford.edu/~tiflo/