[R-sig-ME] lme4 heteroscedasticity???

[Douglas Bates]

It is best to send questions like this to the
R-SIG-Mixed-Models at R-Project.org mailing list, which I am cc:ing on this
reply.  Several of those who read that list can respond more quickly than I
am able to.

As far as I know there is not yet the capability in lme4 to model
heteroscedasticity in the distribution of the response given the random
effects.

On Mon, Oct 13, 2014 at 6:01 AM, Košmelj, Katarina <
Katarina.Kosmelj at bf.uni-lj.si> wrote:

>  Hello,
>
> I am analyzing a mixed model with three crossed factors, two random
> (sample, laboratory) and one fixed (method); the response variable is the
> number of somatic cells in milk.  The main question is: is the precision of
> the means of the three method is comparable? Therefore, I would like to
> compare a model with different variances for the methods with the model
> considering the same variance for the methods.
>
>
>
> In nlme, this is feasible, however, two crossed random factors can not be
> tackled, this can be analyzed with lme4.
>
>
>
> In nlme, the problem of heteroscedasticity if solved. Is this problem
> solved in lme4 yet?
>
> Do you have any suggestion how to deal with this problem?
>
>
>
> Regards,
>
> Katarina
>
>
>

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