[R] storing the estimates from lmer

Göran Broström goran.brostrom at gmail.com
Mon Jul 17 19:59:31 CEST 2006

On 7/15/06, Douglas Bates <bates at stat.wisc.edu> wrote:
> Hi Spencer,
> <rant>
> Some software, notably SAS PROC MIXED, does produce standard errors
> for the estimates of variances and covariances of random effects.  In
> my opinion this is more harmful than helpful.  The only use I can
> imagine for such standard errors is to form confidence intervals or to
> evaluate a z-statistic or something like that to be used in a
> hypothesis test.  However, those uses require that the distribution of
> the parameter estimate be symmetric, or at least approximately
> symmetric, and we know that the distribution of the estimate of a
> variance component is more like a scaled chi-squared distribution
> which is anything but symmetric.

You should add ..."when the true value of the variance is (close to)
zero", I guess. Or does not standard asymptotic ML theory apply to
these models? BTW, what is a
"scaled chi-squared distribution"?


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