R help - Aug 2017 - nlme package, fixing variance.covariance matrix of residuals

Dear R team,

I would like to do a multivariate meta-analysis in R using the nlme package. In
meta-analysis I fix the residuals to known sampling errors. As I do a
multivariate analysis, I have a variance-covariance matrix of sampling errors.
Unfortunately, via varFixed I can only fix a vector of sampling errors and no
matrix.

In the R package metafor using the rma.mv function I can insert the
variance-covariance matrix in the function. I would like to do the same with lme
from the nlme package as nlme provides more flexibility for my model.

Do you now any possibility of doing so in nlme? Are there any changes planned to
incorporate this feature?

Best wishes, I am looking forward to your feedback
Anna-Lena W?lwer

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