This function estimates the population variance of the effect size of
correlated outcomes within a study. That is, it estimates the population
variance from a single draw of a multivariate normal distribution. The function
assumes equal true effect size of all outcomes, equal sampling variances of
the outcomes' effect size, and equal correlation (i.e., r
) among the
outcomes.
For a derivation of this estimator see van Aert & Wicherts (2023).
The variance that is computed with this function can be used to correct for
outcome reporting bias by including the variance as a moderator in a
(multivariate) meta-analysis. Please see van Aert & Wicherts (2023) for
more information.