[R-meta] aggregating effect sizes
Thank you Wolfgang, So if I get correctly, the weighted approach should be preferred if values that I have to aggregate are quite different? Because using the Borenstein vs weighted method gives me quite different results, especially for the mean effect. Thank you! On Mon, 10 Jan 2022 at 12:57, Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:
Dear Filippo, If you are asking about what is described in Box 24.1, then the answer is yes, if you use struct='CS' (which is the default) and 'weighted=FALSE' -- the default in aggregate() is to compute a weighted average, but Borenstein et al. only give the equations for computing an unweighted average and its sampling variance (but since the sampling variances of the two estimates that are being aggregated in the book example are the same, whether one uses weighted=TRUE or FALSE makes no difference). You can also find the corresponding code here: https://wviechtb.github.io/meta_analysis_books/borenstein2009.html#24)_Multiple_Outcomes__Time-Points Best, Wolfgang
-----Original Message----- From: R-sig-meta-analysis [mailto:
r-sig-meta-analysis-bounces at r-project.org] On
Behalf Of Filippo Gambarota Sent: Monday, 10 January, 2022 12:31 To: R meta Subject: [R-meta] aggregating effect sizes Hi, In order to be sure which function to use I would like to ask if the aggregation method of multiple effect sizes with dependent sampling error suggested by Borenstein et al. (2009) is the same as what performed by the aggregate() function in metafor specifying a single correlation. In my case I have calculated pre-post effect size using Morris (2008) and then I have to combine multiple effect sizes calculated on the same pool of subjects. Thank you! -- Filippo Gambarota PhD Student - University of Padova Department of Developmental and Social Psychology Website: filippogambarota Research Group: Colab Psicostat
*Filippo Gambarota* PhD Student - University of Padova Department of Developmental and Social Psychology Website: filippogambarota <https://filippogambarota.netlify.app/> Research Group: Colab <http://colab.psy.unipd.it/> Psicostat <https://psicostat.dpss.psy.unipd.it/> [[alternative HTML version deleted]]