[R] nlme package, fixing variance.covariance matrix of residuals

[Wölwer, Anna-Lena]

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 Wölwer

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