[R-meta] Dear Wolfgang

[Viechtbauer, Wolfgang (SP)]

Dear Ju,

In principle, this might be of interest to you:

http://www.metafor-project.org/doku.php/tips:comp_two_independent_estimates

However, a standardized mean difference is given by (m1-m2)/sd, while a (log) response ratio is log(m1/m2). I see no sensible way of converting the former to the later.

Best,
Wolfgang

>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org]
>On Behalf Of Ju Lee
>Sent: Monday, 13 April, 2020 22:47
>To: r-sig-meta-analysis using r-project.org
>Subject: [R-meta] Dear Wolfgang
>
>Dear Wolfgang,
>
>I hope you are doing well.
>
>My research group is currently working on a project where they are trying to
>compare effect sizes generated from their current mixed-effect meta-analysis
>with effect sizes (based on similar response variables) calculated in other
>meta-analysis publications.
>
>We are currently using log response ratio and are trying to make some
>statement or analysis to compare our grand mean effect sizes with other
>studies. In more details, we are examining how herbivorous animal control
>plant growth in degraded environment. Now, there is already a meta-analysis
>out there that has examined this (in comparable manner) in natural
>environment as opposed to our study.
>
>My colleagues want to know if there is a way to make some type of comparison
>(ex. whether responses are stronger in degraded vs. natural environemnts)
>between two effect sizes from these different studies using statistical
>approaches.
>So far what they have from other meta-analysis publication is grand mean
>hedges'd and var which they transformed to lnRR and var in hopes to compare
>with our lnRR effect sizes.
>
>My view is that this is not possible unless we can have their actual raw
>dataset and run a whole new model combining with our original raw dataset.
>But I wanted to reach out to you and the community  if there is an
>alternative approaches to compare mean effect sizes among different meta-
>analysis which are assumed to have used similar approaches in study
>selection and models (another issue being different random effect structures
>used in different meta-analysis which may not be very apparent from method
>description).
>
>Thank you for reading and I hope to hear from you!
>Best,
>JU