Suppose I run a linear mixed-effects model such as

(fm <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy))

and I want to update the fitting with a new response data (e.g.,
newReaction) with everything else the same as the original model. Dr. Bates
suggested the following on Sept. 5, 2007 to save runtime:

> After fitting the model to the first simulated response, producing the
object 'fm',  the only operations needed to update the model are
>
> fm@y <- newy
> Xy <- cbind(fm@X, fm@y)
> fm@ZtXy <- fm@Zt %*% Xy
> fm@XytXy <- crossprod(Xy)
> lme4:::mer_finalize(fm, verbose)

However, I could not find slots fm@ZtXy and fm@XytXy any more in lme4 nor
lme4a. Have these two slots been changed to different names?

Or essentially the above steps have been wrapped into refit() in lme4?

Thanks,
Gang

	[[alternative HTML version deleted]]


