[R-meta] Mean-adjustment for weighting

[Vojtěch Brlík]

Dear all,

I have conducted a meta-analysis for my bachelor thesis (that means I am
highly inexperienced) using the unbiased standardized mean difference
(Hedges‘ g) as a measure of the effect size. I have noticed recently
published study (https://doi.org/10.1111/2041-210X.12927) suggesting the
adjustment in the standard error calculation as the weights of the effect
sizes are not corresponding to their sample sizes symmetrically. This
inequality causes the biased estimates of pooled effect size variance.

I decided to use this adjustment but it does not cause the same adjustment
in all same-sized studies as the differences between the adjusted and
​non
​-​
adjusted errors are not symmetric (see below the plots in four categories
of effect I want to recalculate
​, also attached below​
).




Please, write me in case you cannot see the figures.

However, the effect size
​s​
remain unchanged and the variance is wider as Doncaster & Spake 2018
suggested.

What is you opinion about this study, do you recommend the use the
adjustment for the standard error calculation or not?

Thank you for your advises and comments.

With kind regards,

Vojtech
​ Brlik​

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