[R] Multi-level Meta-Regression using metafor

[Michael Dewey]

Dear Janina

On 18/11/2016 12:04, Janina Steinert wrote:
> Hi!
>
> I am running a multi-level meta-regression in R using the metafor package.
> I have specified a univariate multi-level meta-regression as follows:
>
> Test_MR <- rma.mv(yi = effectsize_estimates, V = effsize_sd2, data = Test,
>                   mods = ~ x, random = list(~ 1 | coeff, ~ 1 | study))
>
> Can someone help explain what this code specifies exactly? Can I define
> this as a mixed-effects model whereby the moderator X is a fixed effect and
> random effects denote heterogeneity of effect sizes within study clusters
> and between clusters?
>
> Can someone explain what the ~1 at the end of the line specifies?

The ~ sign is part of a formula and the 1 means the intercept so you are 
saying you want a random intercept for each coeff and for each study. 
You are correct that x is the fixed effect of the moderator.

Have you looked at some of the examples on the metafor website? There is 
a whole range there which cover some of the issues you raise. Point your 
browser at http://www.metafor-project.org/ and then look for the tips 
and for the analyses in the navigation panel.

> Thank you!
>
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>
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-- 
Michael
http://www.dewey.myzen.co.uk/home.html