[R-meta] Help with meta-analisys of variation

[Fernando Klitzke Borszcz]

Hi all,

I am conducting a meta-analysis about standard deviations of change between
2 conditions in the metafor package. I am using effect sizes (lnSD) and
their sampling variance, based on Nakagawa et al. (
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/2041-210X.12309).
However, many studies included in my analysis, the same subject produces
multiple results (multiple time points). Thus, I should determine the
variance-covariance matrix of the effects. However, I am not sure if it is
appropriate to determine the variance-covariance matrix using any
correlation value for this type of effect, because effects variances are
based only on the sample size (1/2[n-1]). Is there any alternative to
determine the variance-covariance matrix for this type of data, or I should
just include the study as a random effect?

Best wishes!

Att.
Fernando Borszcz


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