Skip to content
Prev 11072 / 20628 Next

reference for standard error of estimated variance components

Another option for diagnosing problems with the fit is to
compute the Hessian of the variance-covariance parameters, which
are fitted with a Cholesky-factor parameterization ... this
doesn't actually get you the uncertainty of the variance-covariance
matrices, but it gives something that is arguably more useful.
https://github.com/lme4/lme4/issues/120 has some useful machinery
written by Rune Haubo which we eventually hope to integrate into
the package.

  This should be a lot cheaper than likelihood profiling too
(takes only O(p^2) function evaluations where p is the number
of model parameters)

library(lme4)
fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
dd <- update(fm1,devFunOnly=TRUE)
library(numDeriv)
h <- hessian(dd,getME(fm1,"theta"))

Various diagnostics:

rcond(h)
diag(solve(h))
On 13-11-15 08:10 PM, John Maindonald wrote: